Analysis of the market for Doctor of Philosophy (PhD) and economic returns in Cameroon: An archetypical African economy

Abstract

This study examines the extent to which the market for PhDs in the sciences can impact economic returns in Cameroon. The specific objectives address the demand and supply for PhDs and the challenges encountered by these PhDs in the labour market. An ordinal regression model is used to assess the effect of the demand and supply of PhD on economic returnsin Cameroon. The findings reveal a direct and significant relationship between the market for PhDs and economic benefits with respect to years of schooling, experience, sector of employment, abilities of PhD holders and the number of PhD holders in the study area. There is also evidence that the demand for PhDs is high in academia than in industries. Indeed, most PhDs find careers in academia than in the industry due to a mismatch of skills between the demand for skills in industry and the supply of skills by higher education institutions. We propose some recommendations on how to improve the market for PhDs in Cameroon and similar African economies.

1. Introduction

Education is indispensable to the realization of Africa's development agenda and is the foundation of human capital development in developing nations in general. Higher education institutions (HEIs) are considered major organizations for societal transformation and development [1]. Cameroon, like most Least Developed Countries, is a signatory to the United Nations (UN) Sustainable Development Goals (SDGs) covering issues relating to socioeconomic, environmental and technological development. Universities or HEIs offering PhDs are in a unique position to be at the forefront of promoting SDGs, with education being their business and the heart of the Human Capital Theory (HCT). In examining education for sustainable development , Marco [2] articulates that educational response to Sustainable Development Goals (SDGs), which is captured in SDG4 (inclusive, equitable and quality education for all), may enable the attainment of the other SDGs. As such, education is not only a goal in itself but a conduit for other SDGs. Therefore, a PhD, which is the highest degree in academia, may be relevant for the attainment of a development agenda. In other words, HEIs play a dual role in the SDGs as a catalyst for the achievement of the other goals through their roles in human formation, knowledge production, and innovation.

A PhD degree is essentially a research degree [3] and certifies the holder as an independent researcher, an expert with extensive knowledge of a chosen field of study, and a professional with a wide range of transferable skills [4]. A PhD degree holder is expected to bring quality and relevant changes in the economy based on research in the field of study [5]. As such, PhD graduates are important engines for knowledge production which drives innovation and improves the quality of the workforce. These human resources are expected to contribute significantly to economic growth and the development of every economy which is examined in this context as economic returns [6].

Human capital is the sum of skills, talent, knowledge and experience of the people in any organization. Major elements of human capital can be identified as intellectual, social and emotional capital. The quality of human capital determines the level of economic development in any country [7,6,8]. The HCT, initially formulated by Becker (1962) [7] and Rosen (1976) [8], emphasizes the importance of both formal schooling and training in the production process. HCT argues that individual workers have a set of skills or abilities which they can improve on or accumulate through training and education. HCT assumes that personal assets such as skills, education, and physical abilities are fundamental capital that increases one's productivity [9,10]. The impact of PhDs on innovation and economic development takes place through several channels such as the accumulation of scientific capital stock, the enhancement of technology transfers and the promotion of cooperation relationships in innovation processes [5].

Therefore, producing many PhDs could be a plus to a country such as Cameroon which seeks to become a middle-income country by 2035, since education has a direct relationship with productivity. This implies that the more educated an individual is, the more productive they should be. This is why one of the objectives put in place by the government to attain the vision of economic emergence by 2035 is to develop high-level human resources by making the tertiary sector professional, specialized and a source of decent jobs through entrepreneurship, matching job demands with skills development offered and improving on the efficiency of the labour market [11].

Previous research on PhD education has mostly focused on research supervision processes and relationships [12,13,14,[15], [16]], policy responses related to doctoral education [17] and the quality of PhD programmes [18]. While many studies have examined issues relating to the market of PhDs [18,19,[3], [20],21], empirical studies on returns on PhDs have received little attention. In addition, none of such studies known to the researchers have been conducted in Cameroon. There exist significant knowledge gaps on the issue of production and employment of terminal degree holders. This, therefore, necessitates an inquiry into research on PhD markets in Cameroon and how they are likely to impact economic returns. As such, this study evaluates the occupational outcome of PhD holders by calculating their economic returns.

Our study is a first attempt to close this knowledge gap by using a select group of Cameroon universities as a laboratory to study this phenomenon. Cameroon is a representative African economy [22,23,24]. The specific objectives address the following: (1) the demand for PhDs and its effects on economic returns in Cameroon; (2) the supply of PhDs and its effects on economic returns in Cameroon; and (3) the major challenges faced by PhDs holder in the labour market in Cameroon. We set labour market participation as an important determinant of economic returns. Based on these objectives, the study statistically tests the lead hypothesis which examines the significant effects of PhD employment on economic returns in Cameroon. We used the ordinal regression econometric model to assess these effects. Using primary data collected from establishments in Cameroon's leading HEIs, the estimates show direct and significant relationships between the market for PhDs and economic benefits with respect to years of schooling, experience, sector of employment and the abilities of PhD holders. We also show that the demand for PhDs is high in academia than in industries due to a mismatch of skills between the demand for skills in the labour market and the supply of skills by HEIs. The strength of our paper lies in the use of primary data supplemented by key informant reports on a policy-relevant theme on the eve of Cameroon's efforts to redefine its higher education policy. The remainder of the paper examines the theoretical background on the market for PhDs, the nature and source of data as well as the empirical findings complete with discussions of the policy implications. The paper ends with some important conclusions and recommendations.

1.1. Context and justification of the market for PhDs

A PhD is considered the highest qualification and should necessarily affect good governance, democracy, community participation and development most especially in the decision-making process of a country that can enlighten policymakers on the road to economic growth. Also, despite the number of PhD holders, the country's economy does not seem to be witnessing a positive trend as indicated by the World Bank [25] statistics on the annual growth of the Gross National Product (GDP) in Cameroon from 2000 to 2020. The statistics presented a progressive fall in GDP from 2015 to 2020. This can be because of the difficult market for these individuals. A degree is only important when it is productive. The inability of PhDs to participate in the production sector is tantamount to low economic growth. This confirms the study by Fonkeng and Ntembe [22] who found a “significant positive relationship between higher education and economic growth in Cameroon”.

Furthermore, the process of acquiring a PhD is a huge investment to the government, especially in state universities in Cameroon where students pay a registration fee of only 50,000 FCFA (USD 82.61) per year (Decree No. 93/026 of January 19, 1993 to reform the newly created six state universities) while the other expenses are borne by the government. As such, the consistent increase in the production of PhDs in Cameroon has raised the major concern about where these PhDs will go after graduation. Therefore, producing many PhDs is not a problem, but integrating these skills into the labour market is of great relevance to stimulate economic growth and development.

Apart from the state, individuals also benefit (private returns) from investing in education, especially a PhD, which is considered the highest qualification. Each additional year of schooling could generate significant private returns [26] such as higher earnings, better health status, social status, and increase employability. The social and private benefits of education justify the increase in the production of PhDs in Cameroon in varied disciplines as shown in Fig. 1 and Table 1. The information in Fig. 1 shows that in 2010 the Faculty of Science produced 5 PhDs and none for other faculties. In 2012, the Faculty of Science produced 5 PhDs, followed by the Faculty of Education with 3, Social and Management Sciences with 2, Arts with 1 and none for Agriculture and Veterinary Medicine. In 2014, the Faculty of Science produced 3 PhDs, 2 each coming from Arts and Social and Management Sciences and Education 1. The year 2016 had the highest number of PhDs with 16 from the Faculty of Education, followed by Social and Management Sciences with 12, Science with 9, Arts with 3 and the Faculty of Agriculture and Veterinary Medicine with zero. In 2017, the Faculty of Science produced 16 PhDs, followed by Education with 5, Social and Management Sciences with 3 and zero in the Faculty of Arts and Agriculture and Veterinary Medicine. In 2019, the Faculty of Science produces 9 PhDs, followed by Arts with 7, Education and Arts with 3 each and 2 for Agriculture and Veterinary Medicine. In summary, from 2010 to 2019, the Faculty of Science produced 40 PhDs, followed by Education with 35, Social and Management Sciences with 24, Arts with 13 and Agriculture and Veterinary Medicine with 2.

Fig. 1.

Trends in the production of PhDs at the university of buea from 2010 to 2019.

Source: University of Buea Statistics on the Number of PhDs per year: 2010–2019

Table 1.

Trends in the production of PhDs at the university of yaounde 1 (2018–2020).

Faculty	Number of PhDs Produced
	2018	2019	2020	Total
Science	42	97	81	220
Science of Education	03	05	06	14
Medicine and Biomedical Science	01	01	01	03
National Higher Polytechnic	04	05	05	14
Arts, Letters and Human Sciences	40	50	105	195
Total	90	158	198	446

Source: Statistics on the production of PhDs (2018–2020), University of Yaounde 1

Fig. 1 shows that the production of PhDs varies with disciplines and programmes. While the Faculties of Science and Education are experiencing an increase in the production of PhDs at the University of Buea, the Faculties of Social and Management Sciences, Arts and Agriculture and Veterinary Medicine are producing at a relatively low rate. The case seems unsatisfactory in the field of Agriculture. As such, it is observed that the Faculty of Agriculture and Veterinary Medicine has so many part-time lecturers, some without PhDs and has also recruited some PhDs from agricultural institutes such as the Institute of Agricultural Research for Development (IRAD) to improve the productivity of the students. It is important to mention that the University of Buea has a Faculty of Engineering and Technology that was created in 2010 together with the Faculty of Agriculture and Veterinary Medicine but it has not produced a single PhD as of 2021 due to inadequate academic staff to train PhDs. In such situations, it would be difficult to find PhDs in the field of agriculture or engineering being unemployed given the existing demand from these institutions and the reverse is the case with the other discipline which are producing many more PhDs.

The case is not different from the University of Yaounde 1, the mother University of Cameroon, with a high production of PhDs from the Sciences, Arts and Social Sciences. Table 1 presents the production of PhDs in the University of Yaounde 1 from 2018 to 2020. From Table 1, the Faculty of Science produced 220 PhDs between 2018 and 2020; followed by the Faculty of Arts, Letters and Human Sciences with 195. The lowest is from the Faculty of Medicine and Biomedical Sciences with 3 PhDs within three years. It should be noted that universities still experience an increase in individual demand for PhDs. It is observed from the statistics of the Universities of Yaounde 1 and Buea that science (natural sciences) is producing many more PhDs than any other field. The promotion of the natural sciences remains fundamental for human resource formation to anchor industrial development and economic growth. A similar situation is reported in the Organization for Economic Co-operation and Development (OECD) countries that experienced an increase in the production of science doctorates which grew between 1998 and 2008 by nearly 40 % to some 34,000 [27]. The authors noted that this growth showed no sign of slowing as most countries are building up their higher education systems because they see educated workers as a key to economic growth [28]. Based on the background, this study focused on the market for PhDs in the sciences.

1.2. Theoretical nexus of the PhD market

Economics normally sees the value of an item to an individual as the maximum amount of money he/she is willing to pay [29]. Within the context of this study, education determines private and societal benefits, which is particularly true in the case of a PhD. As such, this study focuses on the occupational outcomes of PhDs. This approach is consistent with extant literature on the economic contribution of PhDs [30,5,31,32]

A market is a major framework that allows potential buyers and sellers to exchange goods, services and informatio. Haucap [33] emphasizes that markets are important in enhancing economies of scale, economic prosperity, growth and development. The major factors that determine any market structure are the demand, supply and price of a good or service [34]. The quality and relevance of PhD produced (supply) determine the demand and price (wages or salaries) of PhDs on the market. Literature has identified two major markets for PhDs which are academia and industry [30,19,[20], [35],12,21]. Listening to the voices of some 741 respondents (students, government officials, NGOs and academics) through 55 focused group consultations on their hopes and fears when thinking ahead to possible scenarios for higher education by 2050, the link between higher education and the labour market was a major concern [36].

While they perceive that job market requirements will change with respect to the demand for skills, students remain practical in their perception that a university degree serves to improve their economic and social status. Unemployment is seen as a big threat to the future university's role in teaching students to be “market ready”. However, participants looked beyond the financial benefits of employment to the fulfilment and reward from their chosen area of work. Students are aware of the need to reskill and upskill to maintain stable employment (ibid). The study by Germain-Alamartine et al. [35] reveals that the production of PhDs has increased in Norway, Sweden and the UK due to an increase in public investment to drive innovation. Unfortunately, the academic labour market has not developed at the same pace as the rapid increase in the number of PhDs. As such, most PhDs find employment in industry. Similar research carried out by Ganning and Figueroa [19] on doctoral education and the academic job market in planning shows that 179 out of 270 PhD students in planning preferred to work within academia. Interestingly, 111 out of these 179 PhDs found a position in academia after graduation.

One of the markets identified for PhDs in Cameroon is higher education institutions to strengthen teaching, research and outreach activities. Following independence in 1960, one of the crucial problems faced by the Cameroon government was the need for trained national cadres, especially for senior positions in the civil service. This led to the creation of the University of Yaounde in 1961, today known as the University of Yaounde 1. This university gave birth to six state universities in 1993 under Decree No. 93/026 of January 19, 1993 with the main mission to ameliorate the internal and external efficiencies of higher education in Cameroon [37]. To attain this vision, there was a need for lecturers to run the programmes for the expansion of these newly created universities. As such, most PhD graduates were recruited in state universities. In examining the market for PhDs, Basil and Basil [38] found an inadequate supply of PhDs as a major problem facing business deans in universities in the United States caused by disequilibrium between the demand and supply of PhDs and mismatch between candidates and jobs.

A similar experience is observed by Jones [3] whose study reveals that academia has been a large component of the job market for PhD graduates and are mostly recruited as faculties especially in the humanities and social sciences while most of the graduates from natural sciences and engineering find a career out of academia and usually conduct most of the nation's research and development. In addition, unemployment of PhDs is low in all-natural sciences and engineering fields surveyed and high in the humanities and social sciences which highlights the dearth of non-academic options for those in the humanities and social sciences. This implies while academia accommodates a huge number of PhD graduates, this may vary with fields of study.

The increasing generation and access to knowledge have led to what is now commonly referred to as the knowledge economy [39] which is an engine of productivity as it adds more value to the labour market. If knowledge and information are the new electricity of the economy, then it is a reasonable assumption that the university – as the main knowledge institution in society – will become increasingly important and that its apex training product, the PhD, will appear on the skills radar [40,15]). Therefore, where ever PhDs find a career (academia or out of academia), they are considered resource persons to provide solutions to problems, adapt to change and improve the productivity of the organization through research and development [15].

However, it is becoming more and more difficult for PhD graduates to find a job corresponding to their qualifications [41]. Yet, the world is producing more PhDs than ever before [27]. In Japan, academia has less demand for PhDs: the number of 18-year-olds entering higher education has been dropping, so universities do not need the staff. Neither does the Japanese industry, which has traditionally preferred young, fresh bachelor's graduates who can be trained on the job [27].

The issue of unemployed PhDs, which is expected to be the strength in economic productivity, is a major call for concern. Examining the demand for PhDs by the private and public sectors, academia and outside of academia is relevant to produce PhDs that will efficiently integrate into the labour market and avoid the wastage of valuable human resources. Universities will be able to know the type of PhDs to produce, how to produce and for whom to produce. According to the World Bank [42], education and training do not constitute human capital until they are used effectively as a factor of production. This calls for a need to investigate the market for PhDs which has a significant effect on the development of a nation.

PhD training is part of human capital formation. Human capital is important because it improves productivity in several ways. A doctorate is also a long-term investment rather than a market commodity, the price of which is determined by supply and demand. Our study is thus anchored on the HCT by Becker [7] which considers knowledge and skills from education as an investment in labour productivity. Based on this theory, human capital are not free goods but are products of investments in man [43]. The HCT views schooling as an investment in skills, which contributes to improvements in productivity [44]. Anchoring this study on the HCT assumes that investment in education is necessary to acquire skills and training which, in turn, will increase individual capital. PhD graduates hold the highest education degree, are trained to conduct research and can be considered a key element in the creation, commercialization and diffusion of innovations. This knowledge and skills may increase productivity in the workplace. This increased productivity may bring a higher salary to the individual since the wage of a person, in the ideal labour market, is determined by the person's productivity. Therefore, people would invest in education up to the point where the private benefits from education are equal to the private cost.

Some studies have shown that policy relevant interaction of demand and supply is fundamental to PhD human capital [30,31,45,46,[38], [47]]. For instance, Halse [32], Casey [31] and Basil and Basil [38] examined the value of a doctorate degree both to employers and society and to the economy at large. Their study considers the argument that the production of PhDs can generate benefits for wider society – both because the production process itself generates basic knowledge from which all can take advantage and because the outputs of that process help boost the productivity of those with whom they work. In other words, the gains to society as a whole might be greater than the sum of gains to PhD holders and their immediate employers. However, Servage [46] examined the professional doctorate from the dominant perspective of human capital theory and concludes that human capital theory does not deliver on its promise of status and prosperity for society's most highly educated workers.

Applying this to the present study, individuals and government investment in the production of PhD is justified by the expected private and social returns. According to Tomlinson [48], theories in human capital which underpin much of the current policy agenda in higher education suggest that the economic benefits that accrue from investing in education include a more skilled and flexible workforce, a greater earning capacity for individuals and more career opportunities. It is therefore evident that human capital is a key determinant of economic growth which is also associated with a wide range of private benefits such as better health and well-being.

2. Methodology

2.1. Research design and sample

The study adopted a survey research design of a quantitative approach. This study was carried out in December 2021.. Considering higher education as an investment, it is assumed that being unemployed after two years of graduation is a huge loss to State and individual investments. As such, the sample of the study considered 130 PhD graduates for the 2019 batch and 21 Heads of Department (HODs) in the Faculty of Science in 6 out of 8 state Universities in Cameroon. These are the universities with Faculties of Science which include the Universities of Yaounde I, Douala, Buea, Ngaoundere, Maroua and Dschang. The University of Bamenda has a Faculty of Science but had not produced a PhD at the time this study was carried out in 2021. The Faculty of Science was selected in this study because based on the statistics in the production of PhDs in Cameroon, science is producing the highest number of candidates (see Fig. 1 and Table 1). The choice of HODs is justified by the fact that departments are the technical units of every higher education institution - this is where planning is done to explore new and innovative ways to transform teaching and learning to respond to global trends. As such, they can better respond to the issues related to graduates’ skills and employment.

Purposive sampling was used to select the HODs. Only HODs with at least three years of working experience in their current positions and HODs in departments that produce PhDs were selected for the study. As such, 12 out of 21 HODs were selected for the study. 96 out of 130 PhDs were selected using the Krejcie and Morgan [49] table for selecting a particular sample size for a given population. The proportionate sampling technique was used to select the number of PhD graduates for each university while snowball sampling was used to select each participant for the study. A questionnaire with closed and open-ended questions was used to collect data. The open-ended responses provided an in-depth justification behind the response to the closed-ended questions. As such, findings from the open-ended questions corroborated that of the quantitative findings and provide insights for recommendations on system improvement. Administration of the instrument was done using the face-to-face approach and online using Google Forms.

2.2. Analytical strategy

The quantitative data was analysed using the statistical package for social science (SPSS version 25.0) with the aid of descriptive and inferential statistics. Percentages, frequencies and mean are the descriptive methods used while Pearson test and regression analysis are the inferential statistical tools used in analysing the data collected for the study. The Pearson test was used at the level of correlation analysis because the data for the variables were approximately normally distributed.

Econometric analyses were used to bring out the link between the market for PhDs and economic returns. At the level of regression analysis, an ordinal regression model was used to estimate the overall effect of years of schooling, experience, and employment sector, number of PhDs in a study area and individual abilities of PhD holders on their wage rate. The auto-regression distribution lag was used to estimate the unknown parameter of the multiple regression model. This method was chosen because a change in an economic variable may bring about change in another economic variable beyond time. The results obtained are validated using three criteria; a priori expectation, statistical or first-order test and econometric or second-order test. A Priori expectation is concerned with the magnitude (size) and direction (sign) of estimated parameters. With this criterion, economic theories of the variable and their relationship are made to confirm the stated a priori. This criterion facilitates the determination of the link between the dependent variable and the independent variable. That is, it seeks to establish how years of schooling, experience, employment sector, number of PhDs in a study area and individual abilities of PhD holders on their wage rate.

Economic return is estimated as private and social returns. The drivers of private return were estimated using the following equation adapted from the Mincerian wage regression model [50].

$${nW}_i={\beta }_0+{\beta }_1{S}_i+{\beta }_2{\mathit{Exp}}_i+D_i{\mathit{Sec}}_i+{е}_i$$ (1)

Where ${lnW}_i$ is the natural log of wage, $S_i$ is the years of schooling, ${\mathit{Exp}}_i$ is the experience of an individual and ${\mathit{Sec}}_i$ is the sector in which an individual works (private or public sector); β_i are parameters to be estimated and ${е}_i$ is the error term. Equation (1) is estimated by the Ordinary Least Square (OLS) technique. The regressors are inspired by research which has shown that years of schooling determine the private returns on education in terms of earnings [26] while Germain-Alamartine et al. [35] found individual abilities, experience and skills as relevant determinants of labour market outcome. The labour market for PhDs is either the academia or industry [19,35] which can either be in the private or public sector. Therefore, the major regressors include years of schooling, experience and sector of employment. The Dependent variable is based on Becker's theory of human capital which relates years of schooling and earnings [51]. The Dependent variable here is private returns which are estimated in terms of earnings.

Social benefits (externalities) were assessed using equation (2) adapted from Acemoglu and Angrist [52] and Morreti [53].

$${lnW}_{ijt}={\alpha }_0+{\alpha }_1{P}_{it}+{\alpha }_3{a}_i+{е}_{it}$$ (2)

Where ${lnW}_{ijt}$ is the average wage rate in the study area over time; $P_{it}$ is the number of PhDs in the study area, $a_i$ is individual abilities of PhD holders; ${\alpha }_i$ are parameters to be estimated and ${е}_{it}$ is the error term.

Here, the regressors are assumed to be the Individual abilities of PhD holders, Number of PhDs in the study area. This is supported by Jones [3] who revealed that the market for PhDs varies with the field of study and quantity of production. This is also depicted in Fig. 1 and Table 1 on the production of PhDs in Cameroon. The Dependent variable is Social Returns and it is examined with respect to knowledge production. This is supported by the research works of Lu [54]) and Lešer et al. [55] who found a positive correlation between the training of PhDs and the knowledge-based economy. The IV approach is used to estimate equation (2). The Goodness of fit, the t-test and p-values are used to test the accuracy of the estimated coefficient.

2.3. Findings and discussion

2.3.1. The demand for PhDs

The demand for PhDs examines the extent to which the labour market demand for PhD graduates in the sciences from state universities in Cameroon with regard to the supply of these graduates. Fig. 2 presents the employment status of PhDs before and after graduation. Findings revealed that out of 96 PhDs sampled for the study, 68 % (66) were employed before taking up a PhD as an administrative assistant in the university, an instructor at the university, an assistant lecturer in the university, a teacher in a secondary school, discipline master in a secondary school, laboratory technician and molecular expert in a university laboratory, independent consultant at IPES, and Cadre D'appui Scientifique et Technique à l'IRAD. These observations are similar to the research work of Mouton and Lill [56] on the employment status of South African doctoral graduates. Their study revealed an employment rate of 61 % of doctoral students in South Africa, working either in the public or private sector or being self-employed during their studies. Also, a majority of the students who study full-time are from the natural and life sciences. For example, 66 % and 54 % of students unemployed during their doctoral education were from biological and environmental science and physical and mathematical sciences respectively while health and medical sciences had 31 %. This contradicts the current study as 68 % of the PhD students in the sciences were employed during their studies.

Fig. 2.

Employment status of PhD graduates.

However, among the 30 respondents who were unemployed before taking up their PhD programme, a majority of them 80 % (24) out of the 30 are still unemployed after having their PhD while 20.0 % (6) are employed after their PhD programme. Of those who were employed before taking up a PhD, 59.1 % (39) of secondary school teachers were employed in higher education, 39.4 % (26) of graduates that were already working at higher education institutions without a PhD as either assistant lecturers, instructors, graduate teaching assistants and part-time teachers were recruited as permanent lecturers after their PhD while or 1.5 % (1) was also employed in higher education from another sector. This indicated that PhD holders in the sciences mostly find a career in academia. This is contrary to the findings on a career tracking survey of doctoral holders in Europe by Boman et al. [57] which revealed a high employment rate (95 %) of PhD holders across disciplines, doctorate holders in the humanities had the highest rate of unemployment (9 %) which is two times higher than other disciplines. However, their results on the market for PhDs support the present study as 62 % of the cohort find jobs in academia. They observed that though academia has the highest employment rate, PhDs have the probability of transiting to the private sector due to inadequate job security in academia.

The employment rate of 59.1 % of secondary school teachers shows that most of the PhD students admitted were secondary school teachers. This shows that experience has more impact on PhD market. This is not beneficial to the system because it creates unemployment. Those that were employed before PhD had a high level of employment (60.6 %) after PhD (change of ministry) while those that were unemployed before PhD experienced a high level of unemployment (80.0 %) after acquiring a PhD. This supports the findings that 29 out of the 30 PhD unemployed before taking up a PhD wished to be employed in higher education while 1 of them chooses to be employed in a company. The findings similarly show that even among the respondents employed before taking up their PhD programme, many of them still wish to be employed in higher education. This presents a constraint for the market of PhDs to academia. This corroborates the findings of Ganning and Figueroa [19] on doctoral education and the academic job market in planning which revealed a proxy of 66 % of the students in doctoral studies in planning aspired for a career in academia. In fact, 62 % gained employment in academia after graduation. The research also showed that the number of PhDs who secured positions in academia approximately equals the number of academic positions opened for new PhDs.

However, of the 30 PhDs that were unemployed, only 20 % were employed by January 2022 in higher education institutions and research institutes. For all those that were employed after PhDs, including those that were transferred from one ministry to another, most of them (56.3 %) were employed within three years of obtaining a PhD, 34.4 % took less than a year while 9.4 % took a maximum of four years. This indicates that academia (especially state higher education institutions) remains the largest market for PhDs in Cameroon while working in the industry is questionable. As such, being a PhD without being recruited by the government to teach in a state university has often spurred up conflict between graduates and the government, especially when the supply of doctorates is higher than the demand as experienced in recent years and in the present study. An example is the case where some PhDs in Cameroon went on strike action at the beginning of the year in 2018 for being unemployed despite their status. This led to the special recruitment of 2000 PhDs, following Order No. 132/CAB/PM of December 10, 2018 to lay down the framework for the special recruitment of lecturers in state universities for the years 2019–2021 [58]. Nevertheless, the recruitment had some challenges; the recruitment concerned Cameroonians aged at most 45 years on October 1st, 2019, and holders of a Doctorate or a PhD and falls under the 2019 fiscal year. This restriction led to strike action by some PhDs that were not recruited because they were above 45 years of age. A similar situation occurred in Japan in 2009 where the Science and Education Ministry in Japan offered companies approximately US$47,000 each to take on some of the country's 18,000 unemployed postdoctoral students (one of several initiatives that have been introduced to improve the situation) [27]. This is an indication that the supply of doctorates is greater than the demand in the labour market. This questions the market for PhDs in Cameroon; where can PhDs fit in the labour market? Are PhDs ready to be integrated into the industries?

Based on the findings, an unemployment rate of 80 % of those that were unemployed before taking up a PhD showed an excess of supply over demand for PhDs. The supply of PhDs from higher education institutions is 96, with 30 unemployed while the demand for these PhDs is just 20 % (6). This high rate of unemployed PhDs (80 %) indicates a wastage of private and public expenditure on education, including time spent in acquiring a PhD. Findings revealed that students take an average of 8 years to complete their PhD programme with a minimum of three years and a maximum of 11 years. It is worthy of note that, for all state universities in Cameroon, PhD students pay only a registration fee of 50,000 FCFA (USD 82.80) and incur other costs such as transportation, accommodation, feeding, and research project. The rest of the cost is borne by the government (laboratory, human resource salary and research, didactics and allowances for staff). Findings from the 96 PhD graduates revealed that the average cost (mean) of acquiring a PhD in the sciences in Cameroon is 13,796,774 FCFA (USD 227,48.29) with a minimum of 2,000,000 FCFA (3,297.62 USD) and a maximum of 150,000,000 FCFA (USD 247,321.80).

With all these investments, unemployment has a significant adverse effect on the individual such as poverty which affects the health and wellbeing of the individual and the family. This also affects the economy as taxes from salaries and wages are a significant source of government income. As such, affects the economic development of the country. For an economy to develop, it is expected that the output made from an investment is greater than its input. Yet the demand for PhD studies is on a constant rise. This does not support the attainment of Sustainable Development Goals 1 and 8 which emphasizes no poverty and decent work and economic growth respectively [59].

Apart from employment status, 37.5 % of the PhD graduates reported that nothing has changed after acquiring a PhD, while the others had a salary increase and promotion. Most of those who had salary increases and promotions were teachers in higher education institutions and research institutes without a PhD degree. With a PhD, they are promoted from the rank of an Assistant Lecturer to that of a Senior Lecturer which also comes with an increase in salary in the case of higher education institutions while those in the research institute also change from the grade of a research officer to a senior research officer which also comes with a salary increase. Most of the PhD graduates who reported that nothing has changed after acquiring a PhD are those who were unemployed after acquiring a PhD and those who were employed in the secondary education sector before taking up a PhD and did not succeed to change their ministry. It is worthy of note that, acquiring a PhD as an employee in the secondary education sector in Cameroon has little or no impact on career development. As such, most of the employees in this sector who take up PhD programmes have as objectives to be recruited in the higher education sector as teachers (change of ministry). This is in line with the research work of Ganning and Figueroa [19] where approximately 66 % of the PhD sampled for the study aspired to work in academia.

Table 2 presents a thematic analysis of the experience of participants after acquiring a PhD. In addition, with the response to the close-ended questions, many of the respondents reported that they have experienced an increase in income level after obtaining their PhD. Also, their salary from their job has increased with some saying that they got a new job with higher wages. Also, many of the respondents added that their standard of living has equally improved. A good number of respondents also say that with their PhD, they are better open to the job market with better pay, and have better opportunities to travel and experience other cultures. Furthermore, a few of the respondents added that with their PhD, they have experienced an increase in their research skills, open to career advancement, can think better to solve problems and that they get more societal respect and recognition. These experiences are different to research findings in other contexts such as that of Gibbs and Griffin [60] who found that PhD graduates in biomedical science had greater opportunities to teach in higher education institutions, grant funding and postdoc pay.

Table 2.

Changes experienced after acquiring a PhD.

Themes	Groundings	Responses
Increase income level	29	“Higher income” “Finances have increased. Getting a new job, with a better salary comes with some relief” “More income from part-time job” “Increase in income level”. ‘Financial status is better”
Improve living standard	15	“Improvement in living standard” “I have a more stable family life” “All spheres of life starting from living standard”. “Standard of living due to increase in salary, promotion to higher rank”. “I am now able to live in a house with a modern toilet” “Have a stable finance to take care of my family”
Openness to the job market	10	“Openness to better job opportunities” ‘Getting a job with better pay.” “I have been employed with a salary”. “Adventure; the opportunity to travel and experience other cultures.
Improvement in research skills	4	“Research methods improved” ‘Gaining scientific maturity”
Societal recognition	3	“Self-satisfaction and more respect from society” ‘Better exposure; The PhD has brought me closer to seniors in my field from whom I learn a lot”
Better thinking ability	2	“Capacity to think; as an early career researcher. I have developed the bravery in wanting to solve problems. This is because I no longer have to depend on anyone all the time. In summary, I have found the need to live up to expectations”
Career Advancement	2	“My career, because it enables me to work now in the university” “Opportunities to advance in my career”.

Table 3 presents PhD graduates' satisfaction with their present jobs. Examining PhDs’ satisfaction at their present job, findings from Table 3 revealed that 66.7 % of the PhDs agreed that their job is in line with their career path and degree while 62.5 % agreed that their position at the present job is commensurate with their qualification. In the same line, 50 % agreed that their salary is commensurate with their qualification. This indicates that working in higher education comes with a salary increase and other benefits that attracts teachers from secondary education. Despite these benefits, 58.4 % of the PhDs agreed that their current position is progressively challenging. In aggregate, 59.4 % of respondents with an overall mean of 2.61 slightly above average are satisfied with their present job while 40.6 % of respondents are not. A contrary view was presented by Waaijer et al. [61] in Dutch universities where PhD satisfaction with the current job was linked to their contract of employment and the educational level required for a job. Results revealed that temporary contracts negatively affect job satisfaction and the personal lives of PhD graduates as they cannot obtain a mortgage, stability of family life and the possibility to start a family. Their results also revealed that underemployment of PhD graduates negatively influences their satisfaction in the labour market. A different view was presented by Di Paolo [62] who found that PhDs employed out of academia in Spain are satisfied with the momentary aspect of the job and significantly less satisfied with the non-momentary aspects such as job quality.

Table 3.

PhD holders’ satisfaction at present job.

Items	Strongly Agree	Agree	Disagree	Strongly Disagree	Mean	Total
My position is commensurate with my qualification	15 (20.8 %)	30 (41.7 %)	12 (16.7 %)	15 (20.8 %)	2.42	72
My salary is commensurate with my qualification	12 (16.7 %)	24 (33.3 %)	18 (25.0 %)	18 (25.0 %)	2.67	72
My position is progressively challenging	21 (29.2 %)	21 (29.2 %)	15 (20.8 %)	15 (20.8 %)	2.75	72
My job matches my career path and degree	21 (29.2 %)	27 (37.5 %)	9 (12.5 %)	15 (20.8 %)	2.61	72
Aggregate	69 (24.0 %)	102 (35.4 %)	54 (18.8 %)	63 (21.9 %)	2.61	288

3. Supply of PhDs

The supply of PhDs examines the total number of PhD students admitted in some departments in the sciences within the study area, the prospective job opportunities for these graduates and the total number of PhDs needed by the respective departments. Table 4 presents the number of PhD students admitted in each department for the 2020/2021 academic year as reported by the HODs.

Table 4.

The population of PhD students by Department Sample.

Department	Programme	No. Of PhD students
Biochemistry and Molecular Biology	Biochemistry	33
Geology	Applied Geology	29
Physics	Physics	7
Plant Science	Botany	20
Total		89

In the four departments, the total number of PhD students is 89 with 33 in Biochemistry, 29 in Applied Geology, 20 in Botany and 7 in Physics. It is worthy of note that these departments host different programmes. Out of the 89 PhD students, the HODs reported that they need a total of 16 (33 %) academic staff spread across the various departments. However, they expect the remaining 67 % to find career opportunities elsewhere as shown in Table 5.

Table 5.

Prospective Job Opportunities for PhD graduates.

Departments	Job opportunities
Biochemistry and Molecular Biology	•Teaching in the university •Researcher, •Health facilities, •International organizations
Geology	•Oil companies, •Research institutions, •Universities, •Mining companies
Physics	•Teaching and research
Plant science (Botany)	•Tourism, •Fisheries, •Environment, •Forestry, •Agriculture, •Ministry of Higher Education •National and international NGOs

Results from Table 4 showed that PhD graduates in the sciences have a wide array of opportunities outside of academia. Despite these opportunities, PhD students face several challenges in the labour market as seen in Fig. 3. Of the 12 HODs sampled for the study, 75 % (9) reported that they track the career of PhD holders while 25.0 % (3) of them do not. Fig. 3 presents the findings from HODs and PhD holders on the challenges faced by the labour market.

Fig. 3.

Challenges faced by PhD holders in the labour market (demand and supply of PhDs).

PhDs faced major challenges in the labour market concerning the demand and supply of PhDs as seen in Fig. 3. According to the PhDs and HODs, these challenges have led to a high level of unemployed graduates with PhDs. The major challenges faced with the demand for PhDs in the labour market include meeting the specific job requirement, job mismatch, inadequate laboratories, inadequate space in state universities, inadequate research institutions for the graduates to be integrated and low salaries. As indicated in the following quote by one of the participants: “Jobs are scarce for PhD holders.” Similarly, another PhD student indicated the following: “There are limited opportunities in my specialization. It is difficult to find a job that corresponds to my domain.” This indicated a mismatch between the supply of skills by HEIs and the demand for skills by the labour market. This increases the competition of graduates in the labour market, especially in the private sector. This may be one of the reasons why PhDs complained of low salaries. As such, most of them find a career only in academia, especially the public sector. This study corroborates that of Germain-Alamartin [35] on doctoral education and employment in Catalonia. The study revealed that PhD graduates face a major challenge of skills mismatch in the labour market which affects their preference for a better-paid or more stable job, and the lack of skills development that represents added values in the eyes of the employers.

Because of skills mismatch in the industry, most PhDs struggle for employment in academia for financial security. As indicated by one of the PhD holders: “There are many PhD holders and many wish to work with public universities because of financial security. As such, competition is high”. Unfortunately, there is inadequate space in state universities to accommodate these PhDs. Recently, the government has created three state universities which are expected to go operational in the 2022/2023 academic year. Certainly, this will reduce the number of unemployed PhDs. But just like the other state HEIs have limited space for PhDs, this may be the case with these newly created universities after approximately ten years of existence. Contrary to these results, Suomi et al. [48] identified an oversupply of PhDs, over-education and consistency (doctoral degrees are not respected outside of academia) as some of the challenges faced by PhD graduates in the non-academic labour market. While academia cannot employ all PhD graduates, they also face challenges in integrating into the private sector. In addition, the fabric of the University of the Graduate determines his/her reputation in the job market.

Concerning the supply of PhDs, the first three challenges reflect issues of skills mismatch between the quality of PhDs produced and the needs of the labour market. The first one is the challenge with language. Cameroon is a bilingual country, graduates are expected to speak both languages to have good jobs, especially in the private sector. Bilingualism is one of the soft skills needed in the labour market. As one of the respondents, a PhD student reported: “There is no consideration of language background.” Employers do not care if English or French is your first language or not. You are expected to communicate in both languages. For example, Cameroon has ten regions, two are English speaking while eight are French-speaking. This limits the market for graduates from the English-speaking region who cannot communicate in French. However, English and French are compulsory subjects in all state and private higher education institutions in Cameroon at the undergraduate level. But learning these subjects just to pass an examination or as a means of communication is left in the interest of the learner. Based on the personal experience of the researchers, most graduates from higher education who are bilingual easily find jobs, especially in the private sector.

Graduates and HODs also reported the challenge of inadequate skills and specialization. As reported by one of the participants: “Lack of job and creativity skills.” One of the HODs reported that: “Apart from teaching for a PhD holder, it is difficult to find a job. In addition, most employers think they cannot pay them”. The fact that employers cannot pay PhDs explain their preference for master's or bachelor's degree holders in the industry. As such, one may find PhD holders using their Bachelor's degree to get a job rather than being unemployed. This indicates underemployment and waste of resources in training PhDs. This finding contradicts that of Germain-Alamartine et al. [35] which reveals that most of the PhDs (14 out of 31 and 1 out of 10) desire to work in the industry than academia due to lack of career prospects in academia and the insecurities involved in working on a contract basis and family situation. However, some of their jobs in the industry did not match their qualification as the same jobs could be performed by master's graduates in the same field. This indicates the underemployment of PhD graduates in the labour market.

3.1. Social returns on PhDs

The social return on PhDs was examined concerning its benefit to the university and society at large. This was done using descriptive and inferential statistics. Table 6 presents HODs' opinions on the social returns of PhDs in higher education institutions. Based on the Head of Departments’ opinion on social returns on PhDs recruited in their establishment, cumulatively, 100 % agreed that increase in the number of PhDs in their departments improves research and technical skills, innovative skills, guaranteed high-quality training of students and high-level skills and knowledge production. Similarly, 91.7 % agreed that PhDs improve the analytical skills of teachers while 91 % agreed that teachers with PhD certificates have Subject-specific specialized knowledge and have future leadership potential. In aggregate, 96.4 % of respondents with a high mean of 3.13 on a maximum of 4 indicate that their establishment has benefited from recruited PhD holders while 3.6 % of respondents did not. Among the few heads of department that reported that their establishment has not benefited from the recruited PhD holders, their reason is that the PhD holders recruited in their department had the wrong profile. This supports the findings of Berman and Pitman (2010) which revealed that research-trained professional staff such as PhDs use their research and generic skills in management roles to the benefit of Australian Universities.

Table 6.

Social returns on PhDs recruited in higher education institutions.

Items	Strongly Agree	Agree	Disagree	Strongly Disagree	Mean	Total
Subject-specific specialized knowledge	4 (33.3 %)	7 (58.3 %)	1 (8.3 %)	0 (0.0 %)	3.17	12
Research and technical skills	0 (0.0 %)	12 (100 %)	0 (0.0 %)	0 (0.0 %)	3.00	12
Analytical skills	0 (0.0 %)	11 (91.7 %)	0 (0.0 %)	1 (8.3 %)	2.83	12
Innovative skills	4 (33.3 %)	8 (66.7 %)	0 (0.0 %)	0 (0.0 %)	3.33	12
Guaranteed high-quality training for students	4 (33.3 %)	8 (66.7 %)	0 (0.0 %)	0 (0.0 %)	3.33	12
Future leadership potentials	4 (33.3 %)	7 (58.3 %)	0 (0.0 %)	1 (8.3 %)	3.25	12
High-level skills and knowledge production	0 (0.0 %)	12 (100 %)	0 (0.0 %)	0 (0.0 %)	3.00	12
Aggregate	16 (19.0 %)	65 (77.4 %)	1 (1.2 %)	2 (2.4 %)	3.13	84

An increase in the number of PhDs in the department also increases the number of postgraduate programmes run by the department. Within the context of the study, PhDs have a minimum of one year with research publications and engagement in other research activities to qualify for a change of grade from an assistant lecturer to a senior lecturer which qualifies them to teach and supervise postgraduate programmes and research respectively. This promotion is done by the Joint Recruitment and Promotion Board in Higher Education in Cameroon. As such, HODs reported that an increase in the number of PhDs in their department has increased the number of masters (4) and PhD programmes (3). Table 7 presents the impact of PhDs in the various higher education institutions concerning teaching, research and outreach which are the main mission of HEIs in Cameroon.

Table 7.

The impact of PhD in terms of teaching, research and outreach.

The Impact of a PhD	Themes	Responses
Teaching	Facilitates teaching and research	“They facilitate teaching and research processes” ” It has enhanced teaching making it to be very good”.
	Expansion in scope	“It has expanded the scope of graduate teaching”
	Increase in graduate number	“Increase in graduate number in specific fields”
Number of publications	Increase in the number of publications (15–68)	“This is because teaching is correlated with research and outreach. The overall impact is the increase in the number of publications in the department” “There has been an increase in the number of publications 68”. “There are many publications”. “15”.
Number of community projects, cooperation ties, etc. (outreach)	Two	“Our programme is both laboratory and field base. So, some of the field programmes are in collaboration with other agencies and parastatals such as SOWEDA, CAC, Limbe Botanic Garden, MINFOF, and small-scale flora projects”. “Two”. “Two”
	No impact	“No impact”.

Based on the Heads of Department's opinions on the impact of PhD in terms of teaching number of publications and several community projects, cooperation ties, some of them say the teaching-learning and research process has been facilitated, the scope of graduate teaching has been expanded, and that the number of graduates in some specific field has increased. In terms of the number of publications, all the heads of the Department attest that they have had an increase in their number of publications with the minimum being 15 publications and 68 as the maximum for those who indicated quantitatively. In terms of the number of community projects, and cooperation ties (outreach), some Head of Departments says that they have had two projects while others said none.

Summary statistics in Table 8 revealed that the mean value for private return is 2.89, social returns are 3.13 and that for individual abilities of PhD holders 3.23 on a scale of 1–4. For experience, the mean value is 1.69 on a scale of 1–2. The average year of schooling is 4.67 while the minimum is 3 and the maximum 11. Also, the average number of PhD holders is 22.23 with a minimum of 7 and a maximum of 33. The high standard deviation for years of schooling (1.662) and the number of PhD holders in a study area (2.656) indicate a large disparity.

Table 8.

Summary statistics of the outcome and predictor factors.

	Mean	Std. Dev.	Max-value	Mini-value
Outcome variables
Private returns	2.89	.431	4	1
Social returns	3.13	.565	4	1
Predictors
Years of schooling (number of years used to acquire a PhD	4.67	1.662	3	11
Experience (experience before and during PhD programme)	1.69	.466	2	1
Employment sector (Private and Public)	1.97	.175	2	1
Number of PhD holders in a study area	22.23	2.656	33	7
Individual abilities of PhD holders	3.23	.765	4	1

3.2. Employment of PhD and economic returns: testing of hypothesis

The results in Table 9 computed using the ordinal regression model show that the employment status of PhD holders has a significant, positive correlation with economic returns (p-value 0.035 < 0.05) with those employed contributing more to economic returns (Estimate = 17.602) significant at 0.000 levels than the unemployed (Estimate = 0.511) which is not significant (p-value = 0.578 > 0.05). PhD employment was found to explain a total variability of 35.3 % (Nagelkerke R-Square = 0.353) of the outcome variable (Economic returns in Cameroon). Table 10 presents a correlation matrix between years of school, experience sector of employment, the ability of PhD holders and number of PhD holders and economic returns.

Table 9.

Relationship between PhD employment and Economic Returns in Cameroon.

Economic Returns		Estimate	Std. Error	Wald	p-value	95 % Confidence Interval
						Lower Bound	Upper Bound
		18.244	.422	1872.264	.000	19.070	17.418
PhD employment	Employed	17.602	.575	937.742	.000	18.729	16.476
	Not employed	.511	.919	.309	.578	1.733	2.657
Model Fitting Information					.035
Nagelkerke		.353

Link function: Logit.

Table 10.

Correlation Matrix between Years of school, Experience, Sector of employment, Abilities of PhD holders, Number of PhD holders in the given study area and Economic Returns.

Indicators		Years of schooling	Experience	Sector of employment	Abilities of PhD holders	Number of PhD holders in the study area	Economic returns
Years of schooling	R-value	1	−.221b	.163b	.014	−.189b	.133b
	P-value	.	.000	.001	.780	.000	.009
	N	96	96	96	96	96	96
Experience	R-value	−.221b	1	.266b	−.156b	−.019	.453b
	P-value	.000	.	.000	.002	.710	.000
	N	96	96	96	96	96	96
Sector of employment	R-value	.163b	.266b	1	−.007	.101a	.232b
	P-value	.001	.000	.	.891	.047	.000
	N	96	96	96	96	96	96
Abilities of PhD holders	R-value	.014	−.156b	−.007	1	.042	.266b
	P-value	.780	.002	.891	.	.410	.000
	N	96	96	96	96	96	96
Number of PhD holders in study area	R-value	−.189b	−.019	.101b	.042	1	.073a
	P-value	.000	.598	.005	.244	.	.043
	N	96	96	96	96	96	96

^aCorrelation is significant at the 0.05 level (2-tailed).

^bCorrelation is significant at the 0.01 level (2-tailed).

The findings show that years of schooling (R-value 0.133**, p-value 0.009, <0.05), experience (R-value 0.453**, p-value 0.000, <0.05), sector of employment (R-value 0.232**, p-value 0.000, <0.05), abilities of PhD holders (R-value 0.266**, p-value 0.000, <0.05), and the number of PhD holders in a study area (R-value 0.073*, p-value 0.043, <0.05) has a significant effect on economic returns with experience having more effect wage rate almost two times higher than abilities and sector of employment and almost four times higher than years of schooling while the number of PhD holder in the study area was found to have a very weak effect on economic returns. A contrary view was presented by Jackson and Michelso [63] who linked previous work experience with the employment of PhD graduates in Australia. This supports the findings of Berman and Pitman [64] that research-trained professional staff such as PhDs use their research and generic skills in management roles to the benefit of the university. Their PhD education enables them to identify and solve problems in their current roles in management. Table 9 presents a regression analysis of economic returns on PhDs.

$$\mathbf{M}\mathbf{o}\mathbf{d}\mathbf{e}\mathbf{l}\mathbf{1}\text{Private}\text{returns:}{nW}_i={\beta }_0+{\beta }_1{S}_i+{\beta }_2{\mathit{Exp}}_i+D_i{\mathit{Sec}}_i+{е}_i$$ (3)

Estimates from the ordinal regression analysis show that years of schooling and experience significantly contribute to the private returns of the PhD holders (p-value <0.05) but not the sector of employment (p-value >0.05). However, specifically based on years of schooling, PhD holders with 3–5 years of schooling (Estimate = 2.928), and 6–8 years of schooling (Estimate = 1.702) have higher private returns than those with 9–11 years of schooling (Estimate = 0.977) but, the difference in private returns was not that significant because the lower bond value is less than 1 as observed for 3–5 and 6–8 years of schooling. Based on experience, PhD holders with experience have higher returns (Estimate = 18.104) significant at 0.000 levels than those without experience (Estimate = 8.687) significant at 0.030 levels. This is in line with the descriptive analysis which shows that 98.5 % of the PhDs who were employed before taking up a PhD were employed in higher education (change of ministry) with higher earnings and better opportunities while only 20 % of those that were unemployed before PhD were employed after acquiring a PhD. This supports the assumptions of the human capital theory that education has a direct relationship with earnings, job opportunities and time taken to acquire a job after graduation.

Finally, based on the employment sector presented in Table 11, PhD holders in the public sector have high returns (Estimate = 1.946) than those employed in the private sector (Estimate = 1.594) but the difference is not significant (p-value >0.05) and lower bond less than 1 for both sectors. Years of schooling, experience, and sector of employment explained 44.9 % of the variability on private returns (Nagelkerke = 0.449). This is in line with the descriptive analysis which revealed that most PhD graduates find a career in academia. Those who were employed in the private sector complained of low salaries. This supports the observations of Gaeta, Lavadera and Pastore [65] which revealed that PhDs are overeducated which is detrimental to individual wages which signifies a job-education mismatch for doctoral graduates. According to Gaeta et al. [65], a PhD holder who cannot find a job that allows him to fully utilize his title and skills is detrimental to society as a whole. Being overeducated for a job signifies underemployment which also supports the present study.

$$\mathbf{M}\mathbf{o}\mathbf{d}\mathbf{e}\mathbf{l}\mathbf{2}\text{Social}\text{benefits:}{lnW}_{ijt}={\alpha }_0+{\alpha }_1{P}_{it}+{\alpha }_3{a}_i+{е}_{it}$$ (4)

Table 11.

Ordinal regression analysis for drivers of private returns to PhD.

Private returns		Estimate	Std. Error	Wald	p-value	95 % Confidence Interval
						Lower Bound	Upper Bound
		18.362	.617	885.044	.000	17.152	19.572
Years of schooling	3–5years	2.928	.725	6.641	.019	.492	2.349
	6–8years	1.702	.747	5.199	.023	.239	3.165
	9–11years	.977	.724	1.819	.177	.443	2.396
Experience	Has experience	18.014	.723	620.310	.000	16.596	19.431
	No experience	8.687	.913	56.218	.030	1.789	9.789
Employment sector	Public	1.946	1.024	3.614	.057	.060	3.952
	Private	1.594	.874	3.324	.068	.120	3.308
Model Fitting Information					.013
Nagelkerke		.449

a. Dependent variable: Private returns.

b. Predictors: (Constant): Years of schooling, experience, sector of employment.

The OLS estimate of Equation (4) is presented in Table 12 which shows the overall effects of the number of PhD holders and individual abilities of PhD holders on social returns. A semi-log regression model yielded the best goodness of fit and was hence adapted for the analysis. The goodness of fit of the model is 0.225 indicating that over 23 % of the change in social return is explained by the explanatory variables of the model (number of PhD holders in a study area and individual abilities of PhD holders). The coefficient of the number of PhD holders is positive (0.109) and statistically significant at a 5 % level of probability. This result implies that keeping the other variable constant, a 1 unit increase in the number of PhD holders in a study area will result in on average a 0.109 unit increase in social return.

Table 12.

Regression Analysis Depicting the Overall Effect of the Number of PhD holders and their Abilities on Social Returns.

Variables	Statistics
	Coefficient value	t-value	P-value
Number of PhD holders in a study area (p)	.109	1.594	.046
Individual abilities of PhD holders (a)	.229	2.687	.000
(Constant)	.157
Multiple R	.474
R-squared	.225
Adjusted R squared	.214
Std. Error of the Estimate	.87,970,266
F test	20.530
Prob > F	.000

a. Dependent variable: Social returns.

b. Predictors: (Constant): Number of PhD holders in a study area and individual abilities of PhD holders.

The coefficient of individual abilities of PhD holders is positive (0.229) and statistically significant at a 1 % level of probability. This result implies that keeping the other variable constant, a 1 unit increase in the individual abilities of the PhD holders will result in an average 0.229 unit increase in social return. This is depicted in the descriptive analysis which revealed that an increase in the number of PhDs improves research and technical skills, innovative skills, guaranteed high-quality training of students and high-level skills and knowledge production. This is in line with the findings of Germain-Alamartine et al. [35] that individual abilities/skills determine the labour market outcome of PhD graduates while Suomi et al. [66] identified oversupply of PhDs and overeducation as major factors of the PhD graduates' labour market outcome.

3.3. Conclusion and policy recommendations

In Cameroon, like most African countries, universities remain primordial for a series of functions related to production (such as selection of talents, training and research); to consumption (such as general education, community life and a holding operation); and citizenship (such as socialisation, critical evaluations and democratisation). Beyond these traditional roles, there is increased interest in doctoral studies, with state universities taking the lead to train and hire PhDs. This meets the national development agenda where higher education is recognized as key to delivering the knowledge requirements for development. SDG 4 to which Cameroon has vouched explicitly calls for equal access to tertiary education, including university, as part of the promotion of lifelong learning opportunities for all. Investment in doctoral training and strengthening the research capacities of African universities is now imperative. The central tenet of the HCT holds that high levels of education are essential for the design and production of new technologies, for a country's innovative capacity and development.

This study thus investigated how the market for PhDs in the sciences from public higher education institutions determines the economic benefits in Cameroon. The study explores three major objectives which examine the extent to which the demand for and supply of PhDs affects the economic benefits of Cameroon and the major challenges faced by PhDs in the labour market. Our motivation stems from events in which PhDs in Cameroon went on strike action for not being employed by the government. However, the production of PhDs is still on a constant rise. This raises questions on the market for PhDs and the challenges faced in the job market. Our results show that the market for PhDs in the sciences determined the economic benefits in Cameroon with respect to years of schooling, experience, sector of employment, abilities of PhD holders and number of PhD holders in the study area. An increase in public and private investments in PhD to drive economic and social development has led to the production of many more PhD which is beneficial to the job market because it improves the productivity of the system but the supply of PhDs is more than the demand for these PhDs. This leads to unemployment or underemployment of some PhDs which indicates a waste of scarce resources that should have been devoted to the production of other goods. This does not support the attainment of Cameroon's development agenda of emergence in 2035 and the sustainable development goals.

Unemployment of PhDs forfeits Cameroon's objectives to train skills, decent jobs and match job demands for the efficiency of the labour market [11]. It is echoed in the United Nations report that the attainment of SDG 4 (quality education) enables the attainment of the other SDGs such as health and well-being, gender equality, decent work, responsible consumption and growth and climate change mitigation. In addition, access to quality education ensures social mobility, mitigates the inequality gap and allows people to break the cycle of poverty resulting in the eradication of hunger [67]. Teachers, doctors, and engineers among other professionals decide to acquire higher education qualifications especially PhDs to be more effective and efficient in their professions and support societal goals [1]. These goals cannot be attained with the unemployment of PhDs which questions the quality of skills produced by the education system in response to labour demands. As such, most of PhDs easily find careers in academia than in the industry due to a mismatch of skills between the demand for skills in the labour market and the supply of skills by HEIs. The issue of mismatch of skills indicates that HEIs are producing skills for their consumption and not for the industry. Yet, there are limited spaces in academia to accommodate these graduates. Another challenge faced by these PhDs is that the private sector cannot pay them (underemployment). PhD degree involves a significant investment of money, time and effort. The unemployment of PhDs is a waste of private and public investment made in education.

Findings from this study inform policymakers of the return on the huge investments made in the production of PhDs in Cameroon. It also provides information on how to strengthen the market for PhDs for optimal labour productivity. This study, therefore, recommends the following.

• a)Departments in higher education institutions should strengthen university-industry partnerships to improve on skills acquisition of PhD graduates and their chances of career opportunities in the private sector.
• b)The curriculum should prepare graduates not only for academia but also for integration into industries based on the demand and supply of skills
• c)Admission of PhD students should prioritize unemployed applicants than those that are employed. This will reduce the rate of unemployed PhDs. In addition, recruitment of PhDs in academia should consider more unemployed PhD holders than the employed to reduce unemployment of PhD holders. This will enable supply to meet demand. In addition, PhD holders employed in the order sector should be redeployed with salary increases and more responsibilities to improve the quality of the sector.
• d)PhD training should be geared towards entrepreneurship to encourage self-employment.

Our study is restricted to cross-sectional single-period information, which could be enriched further by time series or panel-data evidence. Again, studying fewer institutions is shrouded with endogenous-related challenges which could have been addressed by increasing the number of institutions studied and the sample size. We also did not explicitly address the issue of inter-university cooperation and internationalization. However, the recommendations provided albeit with the limitations in this study, will contribute to focalising the role of PhD training in the economic emergence of Cameroon, an archetypical African economy. Empirical evidence in other countries suggests a strong association between higher education participation rates and levels of development. With high-quality labour (PhDs), the country will have the capacity to produce more goods and services with limited resources. This will go a long way to improve the gross domestic product in Cameroon and drives economic growth and development. The current study also provides results of the relationship between skills production and the market for PhDs. This information is relevant for higher education institutions to know the type of skills to produce in response to the labour market.

Data availability statement

Data included in article/supp. Material/referenced in article.

CRediT authorship contribution statement

Sophie Ekume Etomes: Writing – review & editing, Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Ernest Lytia Molua: Writing – review & editing, Investigation, Formal analysis, Data curation.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix A. Supplementary data

The following is/are the supplementary data to this article.