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. 2024 Mar 14;19(3):e0296695. doi: 10.1371/journal.pone.0296695

A firm-level analysis of Chinese commercial health insurance surrender

Ling Tian 1,2,, Haisong Dong 1,‡,*
Editor: Eric Fosu Oteng-Abayie3
PMCID: PMC10939191  PMID: 38483859

Abstract

Based on the unbalanced panel data of Chinese professional health insurance companies from 2011 to 2021, the paper constructs "PW+PCSE" model to empirically investigate the main factors affecting the commercial health insurance surrender in China from the company level. The results show that asset-liability ratio has a significant positive effect on health insurance surrender rate. The value preservation and appreciation rate of capital and R&D expenditure rate both have significant negative effects on health insurance surrender rate. These studies bring important enlightenment for domestic health insurance companies to avoid surrender risk.

1. Introduction

Since the reform and opening-up for more than 40 years, China’s commercial health insurance industry develops rapidly [15], at the same time, the surrender amount of the commercial health insurance industry is also high, and the surrender problem is relatively serious [6, 7]. In 2019 and 2020, for example, the surrender amount of several professional health insurance companies increased: the surrender amount of "Ping An Health" was CNY 2.0321 million and CNY 3.1678 million respectively, with a year-on-year growth of 55.89%. The surrender amount of "Ruihua Health" was CNY 0.0285 million and CNY 2.9531 million respectively, which increased 102.62 times year-on-year. The surrender amount of “Kunlun Health” climbed from CNY 79.4485 million to CNY 158.5284 million, an increase of 99.54%.

Surrender means that when the insurance contract is not fully performed, the applicant applies to the insured, the insurer agrees to terminate the legal relationship between the two parties determined by the contract, and the insurer returns the cash value of the policy in accordance with the Insurance Law and the contract. The high surrender rate will directly affect the normal operation of commercial health insurance companies, damage the image of commercial health insurance companies, and is not conducive to the sustainable development of commercial health insurance industry. Based on this, this paper takes the professional health insurance companies in China as the research object (Although there are 164 insurance companies operating health insurance business in China in 2020, due to the diversified insurance business, the surrender amount of commercial health insurance and the breakdown of the financial characteristics of companies operating health insurance business are not disclosed in detail in the annual report, so the research object is targeted at professional health insurance companies), aiming to empirically investigate the main factors affecting the surrender of commercial health insurance in China from the company level, so as to verify the "policy replacement hypothesis" and provide useful value information for the stable development of commercial health insurance.

The original idea of the "Policy substitution hypothesis" was first proposed by Outreville in 1990, and the surrender behavior hypothesis was formally advocated by Russell in 2013. This hypothesis holds that in addition to the external factors in the long-term insurance market, the phenomenon of "poaching" and "grabbing orders" among insurance companies caused by internal competition in the long-term insurance market, as well as the fact that the original policy may lose its advantage due to the changes in the operating conditions of insurance companies in the long-term insurance market, is one of the important factors affecting the surrender behavior. It is believed that the motivation of the policy owner to surrender the policy is that the insurance degree of the original policy is worried and the new policy is favored by the original policy holder in terms of yield, insurance or product rate, so the original policy holder is willing to bear the loss of surrender and chooses to buy the new policy. That is, company-level factor indicators——company operating status [6, 811] and new policy business [1214] are the main influencing factors of long-term insurance surrender.

The asset-liability ratio, as one of the solvency indicators of a company, reflects the degree of protection of the company’s assets to creditors’ rights and interests. The higher the asset-liability ratio, the weaker the company’s long-term solvency and the worsening of the company’s operating condition. Policyholders will opt to surrender the insurance out of concern about the insurance guarantee prospect, which may lead to an increase in the surrender rate [6]. R&D expenditure rate, as one of the company’s stable operation indicators, reflects the intensity of the company’s investment in product development. The higher the R&D expenditure rate, the greater the company’s R&D and technology investment, the stronger the product innovation consciousness, the willingness to design more products to meet the needs of target customers, the stronger the company’s core development ability, and the more opportunities for policy holders to choose suitable policies. Therefore, the surrender rate may be reduced. As one of the indicators of a company’s development ability, the value preservation and appreciation rate of capital reflects the operating efficiency and safety status of the company’s capital. The higher the value preservation and appreciation rate of capital, the stronger the company’s ability to use the capital invested by investors to create profits, the better the company’s capital preservation status, the faster the growth of owners’ equity, and the corresponding protection of creditors’ debts. The stronger the company’s growth, the policy holders have no worries about the personal protection provided by the policy, so the surrender rate may decrease. Based on the above analysis, this paper proposes the following hypotheses:

  • Hypothesis 1. The asset-liability ratio has a significant positive effect on the surrender rate of commercial health insurance.

  • Hypothesis 2. Both R&D expenditure rate and the value preservation and appreciation rate of capital have a significant negative effect on the surrender rate of commercial health insurance.

2. Review of relevant literature

At present, the surrender of life insurance (life insurance here is a broad concept, including commercial health insurance, so these literatures are equivalent to the study of commercial health insurance surrender) is a study on the verification of four classical surrender hypotheses.

In terms of the "emergency fund hypothesis", Outreville (1990) [15] analyzed the deniability of the life insurance market in the United States and Canada during 1955–1979 with data provided by the American Council of Insurers and the International Life Insurance Marketing Research Association, built a multiple linear regression model and found that the unemployment rate had a significant positive effect on the deniability rate. Kuo et al. (2003) [16] collected the data of policy surrender rate of the United States from 1951 to 1998, and built VAR model based on it, investigated the dynamic relationship between unemployment rate, 90-day Treasury bond interest rate and policy surrender rate, and concluded that in the short term, unemployment rate had a more significant impact on policy surrender rate than interest rate. In the long run, interest rate had a more prominent effect on surrender rates than unemployment rate. Kim (2005) [17] took the relationship between the surrender rate and interest rate, policy implementation time, unemployment rate, economic growth rate and seasonal effect as the research purpose, and used the Logit function and complementary Log-Log function successively to model the surrender rate. The results showed that: The Logit model and the complementary Log-Log model are significantly better than the existing Arc-tangent curve model. Unemployment rate, interest rate, economic growth rate, seasonal effect and policy implementation time had highly significant effects on the surrender rate, and the unemployment rate had a significant positive impact on the surrender rate. Jiang (2010) [18] constructed ECM to avoid the problem of white noise in traditional multiple co-integration vectors, and studied the relationship between multiple co-integration vectors and surrender rate. Empirical results showed that "emergency fund theory" and "interest rate replacement theory" were valid in both short and long term, that is, unemployment rate and interest rate had a significant impact on surrender rate. Barucci et al. (2020) [19] investigated the driving factors for the surrender of life insurance contracts of a large Italian insurance company, and found that personal financial/economic difficulties had a significant positive impact on the surrender rate. Cole and Fier (2021) [20] concluded that loan activity was an important factor affecting life insurance surrender. Shim et al. (2021) [21] selected panel survey data of Korean Retirement Income Study (KReIS) with many diverse dimensions to determine which variables had a decisive effect on the lapse and applied the lasso regularized regression model to analyze it empirically and used random forest interpolation to compensate for the missing values. According to the study: (1) In terms of the household variables, the non-existence of old dependents, the existence of young dependents, and employed family members increased the surrender rate. (2) In terms of the individual variables, divorce, non-urban residential areas, apartment type of housing, non-ownership of homes, and bad relationship with siblings increased the surrender rate. (3) In terms of the financial variables, low income, low expenditure, the existence of children that incurred child care expenditure, not expecting to bequest from spouse, not holding public health insurance, and expecting to benefit from a retirement pension increased the surrender rate.

In terms of "interest rate substitution hypothesis", Pesando (1974) [22] mainly analyzed from the perspective of "interest rate substitution theory" and believed that interest rate and surrender rate were significantly positively correlated. The reason was that the rising expected market interest rate increased the expected interest rate of future new products, which decreased the price of new policies and increases the tendency of policy holders to surrender. Babbel (1995) [23] further studied the impact of interest rate changes on the surrender rate of life insurance companies by analyzing the impact of interest rate changes on the cash flow of life insurance companies. After measuring the impact of inflation rate on the cost of life insurance, a conclusion was drawn: the change of interest rate would promote the surrender rate of policy holders, that is, the interest rate had a significant and positive correlation with the surrender rate. Tsai et al. (2002) [24] took the American life insurance market as the sample object, built the VAR model based on the collected surrender rate data, and analyzed the dynamic relationship between interest rate and surrender rate. The research found that there was a significant long-term influence relationship between the two, and the two were highly positively correlated. Knoller et al. (2016) [12] believed that interest rate was an important factor affecting the surrender of traditional life insurance through theoretical analysis. Wei et al. (2019) [8], through qualitative analysis, believed that interest rate had significant influence on life insurance surrender rate, which supported the "interest rate substitution theory".

In terms of the "payment depreciation hypothesis", Babbel (1979) [25] established a model to measure the cost of life insurance, used the net cost-benefit ratio to investigate the impact of inflation rate on the cost of life insurance, and found that: If the premiums and claims of life insurance policies could not be fully adjusted and the policy holders did not have the illusion of money, then the life insurance surrender rate was bound to rise, that is, the inflation rate had a significant positive impact on the surrender rate. Babbel (1981) [26] took the Brazilian life insurance market as the research object and discussed the impact of indexed life insurance policies on the sales of life insurance products under the condition of expected inflation. The research found that: in the period of inflation, indexed life insurance policies failed to solve the problem of high price of life insurance products. The inflation rate would reduce the sales of life insurance products, which indirectly indicates that the inflation rate had a significant and positive correlation with the life insurance surrender rate. Wei et al. (2019) [8], through qualitative analysis, believed that the inflation rate had a significant impact on the life insurance surrender rate, which supported the "payment depreciation theory".

In terms of "policy replacement hypothesis", Mauer and Holden (2007) [9] used public data of the American life insurance market to analyze the impact of corporate financial pressure, product rates, product structure ratio, company size and other factors on the surrender rate of life insurance products. Kiesenbauer (2012) [10] adopted the Logit model to analyze the macroeconomic indicators and operating conditions of 133 German life insurance companies from 1997 to 2009. The study found that: interest rate and contingency fund assumptions only applied to unit-linked operations. The business condition of the company was an important factor affecting the surrender rate of life insurance. Russell et al. (2013) [13], based on the panel data of 51 states in the United States from 1995 to 2009, conducted an empirical test on the "policy substitution" effect affecting the surrender rate in the American life insurance market and found that the ratio of new policies (the proportion of new policies in the total policy premium income) had a significant impact on the surrender rate. Zhan and Chen (2013) [11] constructed a nonlinear Panel Smooth Transition Regression (PSTR) model using non-equilibrium panel data of Chinese life insurance market from 2001 to 2010, and came to the following conclusions: The total assets had a significant positive effect on the surrender rate. The company’s establishment years and the average premium income both had a significant negative impact on the surrender rate. Eling and Kiesenbauer (2014) [14], taking a German life insurance company as the research object, believed that product type or contract age and other product characteristics were important factors affecting the surrender rate. Knoller et al. (2016) [12] made an empirical analysis on surrender behavior of variable annuity contract by using Japanese individual policy data and found that premium income was an important factor affecting surrender of variable annuity contract. Yu et al. (2019) [6] used enterprise-provincial panel data of China’s life insurance industry from 2005 to 2013 to study the determinants of the surrender rate of China’s life insurance industry. It was concluded that the degree of business concentration and the years of establishment of the insurance company had a significant negative impact on the surrender rate. Company size and asset-liability ratio had significant positive impact on the surrender rate. High surrender rates undermined insurers’ financial soundness and hurt new business. Wei et al. (2019) [8] studied the driving factors of life insurance surrender risk in China under the economic crisis, and established the economization model of influencing factors of life insurance surrender rate at the company level. The results showed that the economic situation of insurance companies under the economic crisis was the main factor affecting the life insurance surrender rate.

From the existing research, the research literature on the surrender of commercial health insurance has been relatively rich. The academic contribution and value of this paper are as follows: Firstly, on the basis of previous studies, we continue to try to explore the main factors affecting the surrender of commercial health insurance in China through the empirical study at the company level, so as to verify the "policy replacement hypothesis", which is an academic exploration of great research significance. Secondly, according to the main conclusions, it provides valuable clues for health insurance companies to prevent surrender risks, insurance regulatory departments to formulate corresponding policies and promote the market-oriented reform of commercial health insurance product rates.

3. Study design

3.1 Variable selection and calculation

3.1.1 Explained variables

Commercial health insurance surrender rate: As for the calculation method of surrender rate, the existing literature generally adopts three methods: Method 1 is the surrender fee of this year divided by the premium income of this year; Method 2 is the surrender fee of this year divided by the total payout of this year; Method 3 is the surrender fee of this year/(long-term insurance liability reserve at the end of last year + premium income at the end of this year). The statistical caliber of numerator and denominator of the first two methods is inconsistent, which tends to underestimate or overestimate the surrender rate of the current year [11], resulting in the lack of rationality of the calculation results. Method 3 is the calculation method defined by the former China Insurance Regulatory Commission in the document "Standard for Statistical Analysis Index System of Insurance Companies". This method has the same statistical caliber and can get the surrender rate more accurately. Based on this, this paper adopts the third method to calculate the surrender rate of commercial health insurance. It is used as a quantitative index of commercial health insurance policy surrender in a certain period of time and as an explained variable.

3.1.2 Explanatory variables

Asset-liability ratio: calculated and expressed by dividing the total liabilities by the total assets. R&D expenditure rate: calculated and expressed by dividing R&D expenditure by total operating revenue. Value and appreciation rate of capital: calculated and expressed by dividing owners’ equity at the end of the current year by owners’ equity at the end of the previous year. Foreign-funded group company: Used to indicate whether foreign-funded group company (yes: its value is 1, no: its value is 0), is a dummy variable.

The names, units of measurement, symbols and definitions of the variables are described in Table 1.

Table 1. Definition description of each variable.
Variable name Variable symbol Variable description
Health insurance surrender rate (%) SUR Surrender fund at the end of the current year/(long-term health insurance liability reserve at the end of the previous year + premium income at the end of the current year) ×100
Asset-liability ratio (%) LEV Total liabilities/total assets×100
R&D expenditure rate (%) RDE R&D expenses/Total revenue×100
Value and appreciation rate of capital (%) CRNA Owners’ equity at the end of the current year/owners’ equity at the end of the previous year×100
Foreign-funded group company F_group Dummy variable;Foreign-funded group company or not (Yes = 1, no = 0)

3.2 Data sources

This paper takes "Ping An Health" (PA), "PICC Health" (RB), "Pacific Health" (TPY), "Hexie Health" (HX), "Kunlun Health" (KL), "Ruihua Health" (RH) and "Fuxing United Health" (FXLH) as the research objects. Based on the data of these seven professional health insurance companies from 2011 to 2021, the issue of commercial health insurance surrender is analyzed from the company level. Due to the late establishment of some professional health insurance companies or the lack of public disclosure of information and other reasons, some indicator data are missing in some years. However, in order to preserve the information contained in the existing data as much as possible and improve the efficiency of estimation, the data used in this paper are non-balanced panel data. And because of small n and large T (n = 7, T = 11), it is a non-balanced long panel. Data for all variables are obtained from annual reports of professional health insurance companies. The data preprocessing software is “Excel” and the econometric analysis software is “Stata”. In order to minimize the influence of extreme values on the research results, all data of continuous variables are winsorized based on 15% and 85% quantiles. At the same time, in order to make up for the missing data, the linear interpolation method is used to supplement the missing data.

3.3 Model expression

Generally speaking, the surrender rate of a health insurance company this year is not affected by the surrender rate of the previous year, that is, SURt is not affected by SURt-1. Therefore, this paper considers the static non-equilibrium long panel data model. Chen (2014) [27] pointed out that in the long panel, due to small n and large T, individual dummy variables can be added to the possible individual fixed effects, and time trend items can be added to control the possible time fixed effects. Therefore, the model expression in this paper is set as:

SURit=Xitβ+rTime+ui+εit(i=1,2,,7;t=1,2,,11)

Where, Xit= (LEV, RDE, CRNA)’, is a vector composed of explanatory variables varying with individual and time changes. Time is the time trend item, which is used to control the time effect. ui is individual effect. εit is a random perturbation term that varies with individual and time, and it is independently and equally distributed. cov(εit, ui) = 0, representing the difference in intercept.

4. Empirical analysis

4.1 Multicollinearity test

Before the empirical analysis, the multicollinearity test of independent variables [28, 29] is first conducted, as shown in Table 2. As shown in Table 2, the maximum variance enlargement factor (VIF) of all independent variables is 2.39, far less than 10, indicating that there is no serious multicollinearity problem in the model, and subsequent empirical analysis can be conducted.

Table 2. Multicollinearity test results of independent variables.

Variable VIF value 1/VIF value Result
LEV 2.39 0.419 There is no severe multicollinearity
RDE 1.59 0.627 There is no severe multicollinearity
CRNA 1.33 0.754 There is no severe multicollinearity
Time 1.37 0.731 There is no severe multicollinearity
company
2 2.01 0.497 There is no severe multicollinearity
3 2.01 0.497 There is no severe multicollinearity
4 1.87 0.536 There is no severe multicollinearity
5 2.00 0.499 There is no severe multicollinearity
6 2.20 0.455 There is no severe multicollinearity
7 1.82 0.549 There is no severe multicollinearity

4.2 Stability test and descriptive statistics of variable data

This paper uses unbalanced panel data, so it is necessary to check the stationarity of panel data to avoid the phenomenon of pseudo regression. The stability test method of variable data used in this paper is Fisher-ADF unit root test [3033], and the test results of each variable are shown in Table 3. It can be seen from Table 3 that variables LEV, RDE, CRNA and SUR all pass the 1% significance level test, indicating that the panel data are stationary data, which ensures the accuracy of subsequent empirical analysis. The descriptive statistics of the above stationary variables are shown in Table 4.

Table 3. Stability test results of each variable data.

Variable Fisher-ADF value P-value Result
LEV -6.241 0.0000*** Stable
RDE -4.378 0.0001*** Stable
CRNA -5.164 0.0000*** Stable
SUR -8.519 0.0000*** Stable

Note:

*** is significant at the level of 1%.

Table 4. Descriptive statistics of each variable.

LEV RDE CRNA SUR
Obs 60 60 60 60
Mean 77.521 27.049 134.827 2.959
Std. Dev. 21.447 45.335 82.731 7.686
Max 99.74 353.56 501.81 38.615
Min 4.35 4.31 47.86 0.000
Median 84.065 15.445 111.91 1.089
Skewness -2.182 6.384 2.706 3.979
Kurtosis 7.052 46.409 11.389 17.653

4.3 Inter-group heteroscedasticity test, intra-group autocorrelation test and inter-group coincident correlation test

Since long panel data is used in this paper, the random disturbance item εit may have inter-group heteroscedasticity, intra-group autocorrelation or inter-group covariance, so it needs to be tested. Table 5 shows the test results. Wald test shows that the P value of εit is 0.088, which is significant at the level of 10%, with heteroscedasticity between groups. Wooldridge test shows that εit has heteroscedasticity between groups. Pesaran test shows that there is no inter-group coincident correlation for εit, that is, there are inter-group heteroscedasticity and intra-group autocorrelation problems in this model, which need to be dealt with to ensure the reliability of empirical research results of the model.

Table 5. Test results of inter-group heteroscedasticity, intra-group autocorrelation and inter-group coincident correlation.

Model test type Checks statistical value P-value Result
Inter-group heteroscedasticity test Wald: 12.41 0.088* There is inter-group heteroscedasticity
Intra-group autocorrelation test Wooldridge: 9.395 0.022** There is intra-group autocorrelation
Inter-group coincident correlation test Pesaran: -0.501 1.384 There is no inter-group coincident correlation

Note:

** and * are significant at the level of 5% and 10% respectively.

4.4 Analysis of the empirical results

Table 6: Column (1) is the least square dummy variable method (LSDV) used to estimate the model, and there is no inter-group heteroscedasticity, intra-group autocorrelation or inter-group coincident correlation in the corresponding model. Table 6: Column (2) uses panel correction standard error (PCSE) to estimate the model, and there is inter-group heteroscedasticity or inter-group coincident correlation, but no intra-group autocorrelation in the corresponding model. Table 6: Column (3) is used to estimate the model by “Prais-Winsten” estimation method (i.e."PW+PCSE"), and the corresponding model has inter-group heteroscedasticity or inter-group coincident correlation, and intra-group autocorrelation (assuming the random disturbance term εit follows AR (1) process, and the autoregressive coefficients of each professional health insurance company are the same). Comparing column (1) and column (2), it can be found that the estimation coefficients of the two estimation methods are exactly the same, but the significance of the coefficients is different. Therefore, it can be shown that if the model has inter-group heteroscedasticity or inter-group coincident correlation, but there is no intra-group autocorrelation problem, the estimation coefficients of each explanatory variable will not be changed, but the standard error will be affected. By comparing columns (3) with columns (1) and (2), it is found that the estimated coefficients of “PW+PCSE” are different from those of columns (1) and (2), which indicates that if the model has the problem of inter-group heteroscedasticity or inter-group coincident correlation, and intra-group autocorrelation, it will not only change the estimated coefficients of each explanatory variable, but also affect the standard error.

Table 6. Model estimation results.

Variable (1) (2) (3)
LSDV PCSE PCSE_AR1
LEV 0.0343* (0.0152) 0.0343*** (0.0116) 0.0336*** (0.0108)
RDE -0.0274* (0.0138) -0.0274*** (0.00666) -0.0229*** (0.00656)
CRNA -0.00337 (0.00259) -0.00337* (0.00176) -0.00292* (0.00172)
Time -0.0702* (0.0303) -0.0702*** (0.0166) -0.0641*** (0.0169)
company
2 -1.270*** (0.129) -1.270*** (0.221) -1.237*** (0.262)
3 -0.267 (0.176) -0.267 (0.323) -0.261 (0.414)
4 -1.668*** (0.0788) -1.668*** (0.232) -1.596*** (0.272)
5 -1.715*** (0.170) -1.715*** (0.256) -1.639*** (0.368)
6 -1.294*** (0.224) -1.294*** (0.333) -1.234*** (0.344)
7 -0.650* (0.289) -0.650 (0.463) -0.617 (0.558)
_cons 0.694 (1.341) 0.694 (0.938) 0.518 (0.949)
Obs 60 60 60
R-squared 0.769 0.769 0.668

Note:

*** and * are significant at the level of 1% and 10% respectively.

Based on the problems of inter-group heteroscedasticity and intra-group autocorrelation in the model presented in this paper, and combined with the analysis in the previous paragraph, we can see in Table 6: Among the three estimation results in columns (1)—(3), “PW+PCSE (PCSE_AR1)” is the most robust estimation result. Therefore, PCSE_AR1 is taken as the benchmark regression result of this paper, and the empirical results are mainly analyzed. From Table 6: Column (3), it can be seen that the estimated coefficient of asset-liability ratio (LEV) is 0.0336 (indicating that the surrender rate will increase by 0.0336 for each additional LEV unit), which passes the significance level test of 1%, that is, asset-liability ratio (LEV) has a significant positive effect on the surrender rate, thus Hypothesis 1 can be verified, this is consistent with the conclusion of Yu et al. (2019) [6]. The estimated coefficient of R&D expenditure rate (RDE) is -0.0229 (indicating that the surrender rate will decrease by 0.0229 for each additional RDE unit), which passes the significance level test of 1%, that is, R&D expenditure rate (RDE) has a significant negative effect on the surrender rate. The estimated coefficient of value and appreciation rate of capital (CRNA) is -0.00292 (indicating that the surrender rate will decrease by 0.00292 for each additional CRNA unit), which passes the significance level test of 10%, that is, value and appreciation rate of capital (CRNA) has a significant negative effect on the surrender rate, thus Hypothesis 2 can be verified.

5. Robustness test

In order to ensure the reliability of the empirical conclusions of the above benchmark regression model, the corresponding robustness test is conducted in this paper. The robustness test results are shown in Table 7, where column (1) is the regression of “PW+PCSE (PCSE_AR1)”, so as to compare with the empirical results of the robustness test method. Specifically, two methods are used to verify the stability of the benchmark regression conclusions. Method 1, method of adding explanatory variables, that is, the dummy variable of foreign-funded group companies (F_group) is added into explanatory variables of the model, and a set of estimated results were obtained as shown in column (2). By comparing columns (1) and (2) in Table 7, it can be found that the empirical conclusions of the two are basically consistent, indicating that the baseline empirical estimation results are robust. Method 2, method of deleting explanatory variables, that is, deleting the value and appreciation rate of capital (CRNA) in explanatory variables of the model. Another set of estimated results is shown in column (3). By comparing columns (1) and (3) in Table 7, it can be found that, compared with the regression of “PW+PCSE (PCSE_AR1)”, the estimation coefficient, influence direction and significance level of each explanatory variable have not changed in general, that is, the empirical results of the benchmark are still robust. To sum up, the benchmark empirical conclusions of this paper have good stability.

Table 7. Model robustness tests.

Variable (1) (2) (3)
PCSE_AR1 PCSE_1 PCSE_2
LEV 0.0336*** (0.0108) 0.0336*** (0.0108) 0.0331*** (0.0104)
RDE -0.0229*** (0.00656) -0.0229*** (0.00656) -0.0240*** (0.00607)
CRNA -0.00292* (0.00172) -0.00292* (0.00172)
Time -0.0641*** (0.0169) -0.0641*** (0.0169) -0.0572*** (0.0160)
F_group (omitted)
company
2 -1.237*** (0.262) -1.237*** (0.262) -1.220*** (0.244)
3 -0.261 (0.414) -0.261 (0.414) -0.290 (0.436)
4 -1.596*** (0.272) -1.335*** (0.260) -1.681*** (0.266)
5 -1.639*** (0.368) -1.639*** (0.368) -1.636*** (0.310)
6 -1.234*** (0.344) -0.973*** (0.366) -1.256*** (0.341)
7 -0.617 (0.558) -0.356 (0.479) -0.533 (0.540)
_cons 0.518 (0.949) 0.257 (0.974) 0.196 (0.906)
Obs 60 60 60
R-squared 0.668 0.668 0.659

Note:

*** and * are significant at the level of 1% and 10% respectively.

6. Endogenous description

Generally speaking, the better the operating condition of the insurance company, the smoother the development of the insurance company, the smaller the chance of surrender; At the same time, the lower the surrender rate of the insurance company, it will also have a positive impact on the operating status of the insurance company, which is conducive to improving the financial status of the insurance company. Therefore, it is easy to have endogeneity problems in the selection of proxy variables for corporate financial characteristics. In the process of explaining variable selection, this paper does not use the absolute value of variables such as total assets, total liabilities, total owners’ equity, R&D expenses and total operating revenue, but adopts the relative size of different variables. For example, the increase in the total liabilities of a health insurance company does not necessarily lead to the increase in the ratio of the total liabilities of the health insurance company to the total assets (i.e., asset-liability ratio:LEV), thus avoiding the possible endogenous problems in the model [34].

7. Conclusions, implications, and prospects

7.1 Conclusions

Based on the non-equilibrium long panel data of Chinese professional health insurance companies from 2011 to 2021, this paper constructs a “PW+PCSE” model, and empirically examines the main factors affecting the surrender of Chinese commercial health insurance from the company level. The main conclusions of this paper are as follows: firstly, there is a significant positive correlation between LEV and SUR. Secondly, both the rate of R&D expenditure (RDE) and the rate of value and appreciation of capital (CRNA) have a significant negative effect on the surrender rate of health insurance (SUR).

7.2 Policy enlightenments

Based on the above main research conclusions, the policy enlightenments of this paper are as follows:

  1. Strengthen asset and liability management of health insurance companies and control asset-liability ratio. Assets and liabilities management is the unified and coordinated management of assets and liabilities by health insurance companies according to the changes of economic environment and their own business conditions. Due to the significant positive correlation between the asset-liability ratio and the surrender rate, Chinese health insurance companies should pay attention to strengthen the management of assets and liabilities, reasonably arrange the insurance asset portfolio according to the characteristics of the insurance liability portfolio, and control and reduce the asset-liability ratio [35]. By matching the cost and benefit, maturity, nature and scale of assets and liabilities, we can guarantee the virtuous cycle of funds and the solvency of commercial health insurance companies and realize the coincidence of assets and liabilities cash flow.

  2. Establish a sound research and development system for health insurance products, and stabilize the R&D expenditure rate. Due to the significant negative correlation between R&D expenditure rate and surrender rate, Chinese health insurance companies should actively establish a perfect system of commercial health insurance product development, and steadily increase the rate of R&D expenditure. A perfect commercial health insurance product research and development system should be a gradual and cyclic process, that is, market research, planning and demonstration, product design, training and promotion, exhibition sales, information feedback, supervision and assessment. Design and develop products according to the full and detailed market survey results, and improve and perfect the products through the feedback mechanism after the sale of new products, which can effectively avoid the problem of homogeneity and singleness of products, but also can keep the health insurance company’s product research and development ideas active, and achieve product innovation. Health insurance companies should set up special funds for product research and development, determine the product positioning and scope suitable for their own characteristics, implement product differentiation strategy, design flexible and diversified products to meet the actual needs of target customers and reduce the occurrence of surrender of insurance.

  3. Strengthen the asset management level of health insurance companies and raise the value and appreciation rate of capital. Since there is a significant negative correlation between the value-added rate of capital preservation and the surrender rate, Chinese health insurance companies should optimize the asset portfolio of insurance companies and strive to improve asset returns to realize capital preservation and appreciation. At present, the capital investment of Chinese health insurance companies is still excessively concentrated in bank deposits and bonds, and there is a risk of concentrated allocation. With the promulgation of the Interim Measures on the Management of the Use of Insurance Funds (revised version), the investment of insurance funds can be extended to unlisted equity, real estate, mortgage loans and other new assets, so as to expand the space of insurance asset allocation. In addition, the investment effect of the assets of health insurance companies is closely related to the choice of investment organization mode. Investment organization mode is an effective means to ensure investment returns and prevent investment risks. Health insurance companies should adopt more specialized investment organization mode to further improve the value and appreciation rate of capital.

7.3 Research prospects

In the study of the impact of company-level characteristics on commercial health insurance surrender, this paper examines the direction, size and significance of the effect on commercial health insurance surrender from three perspectives: asset-liability ratio (corporate solvency index), value and appreciation rate of capital (corporate development ability index) and R&D expenditure rate (corporate stable operation index). However, the company-level characteristics are not limited to this, but also cover many aspects, such as the company’s establishment years, policy dividend level, policy premiums per unit, the company’s business procedures rate and so on. Due to the feasibility of the empirical model selected, this paper does not discuss these aspects, and these factors are rarely involved in existing literature, so it can be the future research direction of scholars at home and abroad. This paper considers that these variable data can be obtained through the annual reports disclosed publicly by companies or through field visits to companies, and accordingly, appropriate empirical methods and models are selected to carry out relevant further research.

Supporting information

S1 Data

(XLS)

pone.0296695.s001.xls (39.5KB, xls)
S1 File

(DOC)

pone.0296695.s002.doc (254.5KB, doc)

Data Availability

All relevant data are within the manuscript and its Supporting information files.

Funding Statement

The author(s) received no specific funding for this work.

References

  • 1.Xu B C, Xu X N, Zhao J C, Zhang M. Influence of Internet Use on Commercial Health Insurance of Chinese Residents. Frontiers in Public Health. 2022, 10:907124. doi: 10.3389/fpubh.2022.907124 . [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Tian L, Dong H S. Family Life Cycle, Asset Portfolio, and Commercial Health Insurance Demand in China. International Journal of Environmental Research and Public Health. 2022, 19(24):16795. doi: 10.3390/ijerph192416795 . [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 3.Yang P, Chen Z P. Optimal time-consistent social health insurance and private health insurance strategy under a new health insurance framework. Applied Stochastic Models in Business and Industry. 2022, 38(4):726–743. doi: 10.1002/asmb.2683 [DOI] [Google Scholar]
  • 4.Li C, Wang S F, Liu X H, Wang L. Does the Development of the Insurance Industry Promote the Purchase of Rural Commercial Health Insurance? Frontiers in Public Health. 2021, 9:695121. doi: 10.3389/fpubh.2021.695121 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5.Tian L, Dong H S. Study on the Dynamic Relationship between Chinese Residents’ Individual Characteristics and Commercial Health Insurance Demand. International Journal of Environmental Research and Public Health. 2023, 20(6):4797. doi: 10.3390/ijerph20064797 . [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 6.Yu L, Cheng J, Lin T T. Life Insurance Lapse Behaviour: Evidence from China. Geneva Papers on Risk and Insurance-Issues and Practice. 2019, 44(4):653–678. doi: 10.1057/s41288-018-0104-5 [DOI] [Google Scholar]
  • 7.Hilpert C. The effect of Risk Aversion and Loss Aversion on Equity-Linked Life Insurance with Surrender Guarantees. Journal of Risk and Insurance. 2020, 87(3):665–687. doi: 10.1111/jori.12297 [DOI] [Google Scholar]
  • 8.Wei Z Y, Zheng H T, Zhang W R. Research on the Driving Factors of Life Insurance Companies’ Surrender Risk under Economic Crisis. Bingzheng C, Powers M R. Proceedings of 2019 China International Conference on Insurance and Risk Management (CICIRM). Beijing: Tsinghua University Press, 2019: 634–643.
  • 9.Mauer L, Holden N. Determinants of the Lapse Rate in Life Insurance Operating Companies. Review of Business. 2007, 28(1):54–64. [Google Scholar]
  • 10.Kiesenbauer D. Main Determinants of Lapse in the German Life Insurance Industry. North American Actuarial Journal. 2012, 16(1):52–73. doi: 10.1080/10920277.2012.10590632 [DOI] [Google Scholar]
  • 11.Zhan K, Chen H. An empirical study on influencing factors of surrender of life insurance policies in China: Based on microdata at the firm level. Insurance Research. 2013(6):59–67. (In Chinese) https://kns.cnki.net/kcms2/article/abstract?v=JxCH2R2Ogon_Qg8wfLLmY4zPE9WH_-Rqww6auum4W2hsSRQjTndwy2tWD64jOCyBnxuuCQOf5m6x2twO7sZRfJjDhTPUKTU19-1aqhhztSpQTBoLT8u4mSMhnuAIcuzavQG9-4xAEq0=&uniplatform=NZKPT&language=CHS [Google Scholar]
  • 12.Knoller C, Kraut G, Schoenmaekers P. On the Propensity to Surrender a Variable Annuity Contract: An Empirical Analysis of Dynamic Policyholder Behavior. The Journal of Risk and Insurance. 2016, 83(4):979–1006. doi: 10.1111/jori.12076 [DOI] [Google Scholar]
  • 13.Russell D T, Fier S G, Carson J M, et al. An Empirical Analysis of Life Insurance Policy Surrender Activity. Journal of Insurance Issues. 2013, 36(1):35–57. [Google Scholar]
  • 14.Eling M, Kiesenbauer D. What Policy Features Determine Life Insurance Lapse? An Analysis of the German Market. The Journal of Risk and Insurance. 2014, 81(2):241–269. doi: 10.1111/j.1539-6975.2012.01504.x [DOI] [Google Scholar]
  • 15.Outreville J F. Whole-Life Insurance Lapse Rates and the Emergency Fund Hypothesis. Insurance: Mathematics and Economics. 1990, 9(4): 249–255. doi: 10.1016/0167-6687(90)90002-U [DOI] [Google Scholar]
  • 16.Kuo W Y, Tsai C H, Chen W K. An Empirical Study on the Lapse Rate: the Cointegration Approach. Journal of Risk and Insurance. 2003, 70(3):489–508. doi: 10.1111/1539-6975.t01-1-00061 [DOI] [Google Scholar]
  • 17.Kim C K. Modeling Surrender and Lapse Rates with Economic Variables. North American Actuarial Journal. 2005, 9(4):56–69. doi: 10.1080/10920277.2005.10596225 [DOI] [Google Scholar]
  • 18.Jiang S. Voluntary Termination of Life Insurance Policies: Evidence from the US Market. North American Actuarial Journal. 2010, 14(4):369–380. doi: 10.1080/10920277.2010.10597596 [DOI] [Google Scholar]
  • 19.Barucci E, Colozza T, Marazzina D, Rroji E. The Determinants of Lapse Rates in the Italian Life Insurance Market. European Actuarial Journal. 2020, 10(1): 149–178. doi: 10.1007/s13385-020-00227-0 [DOI] [Google Scholar]
  • 20.Cole C R, Fier S G. An Examination of Life Insurance Policy Surrender and Loan Activity. Journal of Risk and Insurance. 2021, 88(2):483–516. doi: 10.1111/jori.12329 [DOI] [Google Scholar]
  • 21.Shim H, Min J Y, Choi Y H. Household, Personal, and Financial Determinants of Surrender in Korean Health Insurance. Communications for Statistical Applications and Methods. 2021, 28 (5):447–462. doi: 10.29220/CSAM.2021.28.5.447 [DOI] [Google Scholar]
  • 22.Pesando J E. The Internet Sensitivity of the Flow of Funds through Life Insurance Companies: an Econometric Analysis. Journal of Finance. 1974, 29(4):1105–1121. doi: 10.2307/2978387 [DOI] [Google Scholar]
  • 23.Babbel D F. Asset-Liability Matching in the Life Insurance Industry. The Financial Dynamics of the Insurance Industry (Edited by Altman E. I. and Vanderhoof I. T.). New York: Irwin Professional Publishing, 1995. [Google Scholar]
  • 24.Tsai C H, Kuo W Y, Chen W K. Early Surrender and the Distribution of Policy Reserves. Insurance: Mathematics and Economics. 2002. (31): 429–445. doi: 10.1016/S0167-6687(02)00188-9 [DOI] [Google Scholar]
  • 25.Babbel D F. Measuring Inflation Impact on Life Insurance Costs. Journal of Risks and Insurance. 1979, 46(3):316–342. doi: 10.2307/252457 [DOI] [Google Scholar]
  • 26.Babbel D F. Inflation, Indexation, and Life Insurance Sales in Brazil. Journal of Risk and Insurance. 1981, 48(1): 111–135. doi: 10.2307/252655 [DOI] [Google Scholar]
  • 27.Chen Qiang. Advanced Econometrics and stata Applications. Second Edition. Beijing: Higher Education Press, 2014. (In Chinese). [Google Scholar]
  • 28.Milenkovic N, Kalas B, Mirovic V, Andrasic J. The impact of macroeconomic determinants and tax form on inflation in selected Balkan countries. Serbian Journal of Management. 2019, 15(1): 7–18. doi: 10.5937/sjm15-16685 [DOI] [Google Scholar]
  • 29.Okunlola O C, Ayetigbo O A. Economic Freedom and Human Development in ECOWAS: Does Political-Institutional Strength Play a Role? Journal of the Knowledge Economy. 2022, 13(3): 1751–1785. doi: 10.1007/S13132-021-00787-W [DOI] [Google Scholar]
  • 30.Herzer D, Strulik H. Religiosity and income: a panel cointegration and causality analysis. Applied Economics. 2017, 49(30):2922–2938. doi: 10.1080/00036846.2016.1251562 [DOI] [Google Scholar]
  • 31.Jumanne B B,Keong C C. Ownership concentration, foreign ownership and corporate performance among the listed companies in East African community: the role of quality institutions. African Journal of Accounting, Auditing and Finance. 2018, 6(1):70–90. doi: 10.1504/AJAAF.2018.10012250 [DOI] [Google Scholar]
  • 32.Liang C Y, Liu Z Y, Geng Z F. Assessing e-commerce impacts on China’s CO2 emissions: testing the CKC hypothesis. Environmental science and pollution research. 2021, 28(40):56966–56983. doi: 10.1007/s11356-021-14257-y [DOI] [PubMed] [Google Scholar]
  • 33.Wang L H, Liu G H, Alkhatib S, Wang X Y, Dai J P, Abbas S Z, et al. The impact of foreign direct investment on environment: evidence from newly industrialized countries. Environmental science and pollution research. 2022, 29(47):70950–70961. doi: 10.1007/s11356-022-20781-2 [DOI] [PubMed] [Google Scholar]
  • 34.Zou W, Fan Z Z. An empirical study on financial support for the construction of Guangdong-Hong Kong-Macao Greater Bay Area: Based on Intercity panel data. Exploration of International Economy and Trade. 2018, 34(5):55–67. (In Chinese) https://kns.cnki.net/kcms2/article/abstract?v=JxCH2R2Ogonbb7BdeZEwLOhm8V8wnrljnL5P75zWB_jreY0_eech_5tFNCf1vKDlt0KgoyqJzTvqOt4MtsKyOYsXBhDfxxSx0sg1TQoCRoJW-VPb6YUJx0Tlar_NtkPR-ila6yWlSWMhDbWWchpqGA==&uniplatform=NZKPT&language=CHS [Google Scholar]
  • 35.Zhang L, Fakieh B, Shang L. Financial Management of Asset-Liability Ratio of Small- and Medium-Sized Enterprises in Dynamic Nonlinear System. Fractals-Complex Geometry Patterns and Scaling in Nature and Society. 2022, 30(2): 2240064. doi: 10.1142/S0218348X22400643 [DOI] [Google Scholar]

Decision Letter 0

Eric Fosu Oteng-Abayie

1 Sep 2023

PONE-D-23-17007A Firm-level Analysis of Chinese Commercial Health Insurance SurrenderPLOS ONE

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Reviewer #1: The paper provides valuable insights into the determinants of commercial health insurance surrender in China, utilizing data from seven health insurance companies over an eleven-year period. However, I would like to offer some constructive feedback on the organization of the paper, specifically regarding the introduction, study design, and empirical analysis sections. While the literature review is well-developed and articulated, there are some issues with conceptual clarity in the aforementioned sections. I would like to highlight the following concerns:

1. The authors mention that there are 168 commercial health insurance companies in China as of 2020, but the study only includes data from seven companies. It would be helpful if the authors could provide an explanation for this selection of only seven companies.

2. The introduction section seems to include descriptive statistics, which would be better placed in the empirical analysis section. The introduction should focus on providing background information and addressing the research gap the study aims to fill. Table 1 should be moved to the empirical analysis section, and a condensed version of Section 3 (Theoretical Analysis and Research Hypothesis) should be integrated into the introduction section.

3. The statements in lines 192 to 205 appear to be the authors' own conjectures without proper citations. It is essential to support these statements with relevant theoretical and empirical literature.

4. The study design section lacks comprehensive explanations. The selected panel data econometric model, the fixed effect least square dummy variables (LSDV) model, should be described in detail in the study design section. It would be helpful to clarify why this specific model was chosen over other panel data models and provide information on the statistical (econometric) tests to be conducted and the reasoning behind them. Additionally, robustness checks should be discussed in the study design section, rather than in the empirical results section.

5. Table 3 should be relocated to the empirical results section for better coherence.

6. The results of the various statistical tests (Tables 4, 5, and 6) should be placed in the appendix or supplementary material section, rather than within the main body of the paper.

Taking these suggestions into consideration will enhance the clarity and structure of the paper.

Reviewer #2: Comment 1

The introduction is generally fine in it's current state. However, the motivation for this study is completely missing. The contribution of the study is poorly stated and disorganized. It is utterly confusing the purpose of the literature mentioned. The authors should give a clear distinction between this study and existing studies, and provide a clear literature gap.

Comment 2

The introduction section also did not touch on the main issues in the topic. The authors should conceptualize the terms in the study well and also bring out what other studies have done in this area and what this study seeks to add.

Comment 3

In the literature review section, the authors should first explain the meaning of commercial health insurance surrender and critically evaluate the literature: Instead of simply summarizing the findings of each study. Discuss any inconsistencies in the existing literature and highlight areas where further research is needed.

Comment 4

The authors should change the interpretation of results presented in line 327 to 336. Regression and correlation are not the same. Regression shows an effect of one variable on the other and correlation shows linear association.

Comment 5

The authors should discuss the significance of the coefficients in the regression analysis. It would be useful to provide some economic or practical significance to these findings. Additionally, the authors could compare the findings to existing literature or theoretical expectations to provide a more comprehensive analysis.

Comment 6

The conclusion of the study is weak, the authors need to indicate the major factors that must be improved to reduce surrender rate in insurance sector in China.

Reviewer #3: The following are suggestions to improve the quality of the work

* There is the need to offer justification for focusing on health insurance surrender in China. What is the current situation? what is/are the likely implications if the trend remains same? What are the related policy issues that warrant this study.

* The discussion of the results should be improved. For each KEY variable tell the effect it has on "surrender" and offer possible reasons for the outcome in China. Relate the discussion to the literature and previous empirical studies/findings.

**********

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Reviewer #1: Yes: Kwadwo Arhin

Reviewer #2: No

Reviewer #3: No

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PLoS One. 2024 Mar 14;19(3):e0296695. doi: 10.1371/journal.pone.0296695.r002

Author response to Decision Letter 0


27 Sep 2023

Response to Reviewers

Reviewer #1:

1. The authors mention that there are 168 commercial health insurance companies in China as of 2020, but the study only includes data from seven companies. It would be helpful if the authors could provide an explanation for this selection of only seven companies.

Response:

Thank you very much for your comments. Based on your suggestions, we have explained this accordingly. See the red brackets in "1.Introduction" for specific modifications.

Thanks again for the reviewer's suggestions.

2. The introduction section seems to include descriptive statistics, which would be better placed in the empirical analysis section. The introduction should focus on providing background information and addressing the research gap the study aims to fill. Table 1 should be moved to the empirical analysis section, and a condensed version of Section 3 (Theoretical Analysis and Research Hypothesis) should be integrated into the introduction section.

Response:

Thank you very much for your comments. Based on your suggestions, we have expanded and modified "1 Introduction", for details, see the red part of "1.Introduction". However, we choose to leave Table 1 in the "Introduction", because Table 1 is a brief introduction to each professional health insurance company, so that readers can understand the basic information of each professional health insurance company in China more quickly. Therefore, please kindly understand our approach..

Thanks again for the reviewer's suggestions.

3. The statements in lines 192 to 205 appear to be the authors' own conjectures without proper citations. It is essential to support these statements with relevant theoretical and empirical literature.

Response:

Thank you very much for your comments. Based on your suggestion, we have added relevant quotations to lines 192 to 205, mainly adding the literature that asset-liability ratio has a significant positive impact on surrender rate, because there have been empirical studies on this and reached the same conclusion as this paper. In addition, the significant impact of R&D expenditure rate and capital preservation and appreciation rate on surrender rate, It is the extended research finding of this paper to verify the "policy replacement hypothesis" (at the company level), which is the innovation point of this paper, and this part is the theoretical analysis part of our paper. For details, see lines 192 to 205.

In addition, we attach the relevant literature cited for reference by the reviewers. Attached:

Yu L, Cheng J, Lin T T. Life Insurance Lapse Behaviour: Evidence from China. Geneva Papers on Risk and Insurance-Issues and Practice. 2019, 44(4):653-678. https://doi.org/10.1057/ s41288-018-0104-5

Thanks again for the reviewer's suggestions.

4. The study design section lacks comprehensive explanations. The selected panel data econometric model, the fixed effect least square dummy variables (LSDV) model, should be described in detail in the study design section. It would be helpful to clarify why this specific model was chosen over other panel data models and provide information on the statistical (econometric) tests to be conducted and the reasoning behind them. Additionally, robustness checks should be discussed in the study design section, rather than in the empirical results section.

Response:

Thank you very much for your comments. First, in accordance with your suggestions, we separate the Robustness test and Endogenous statement from the section on "Empirical Analysis" and make them a separate section, with modifications in "6. Robustness test" and "7. Endogenous description".

In addition, we divided three small parts in "4 Research Design", and the third part may cause misunderstanding. Therefore, we changed "4.3 Model setting"to "4.3 Model expression", that is, we modified the part title. Section 4.3 is intended to introduce the model expression. In the model expression, we explain why we are adding a “time trend term” instead of a "time dummy variable" in the usual sense. As for what kind of estimation method is adopted for "long panel data with variable intercept statically unbalanced", through a series of tests in the "5 Empirical Analysis" chapter we concluded that "PW+PCSE" estimation method is the most appropriate estimation method, rather than "LSDV" estimation method.

Thanks again for the reviewer's suggestions.

5. Table 3 should be relocated to the empirical results section for better coherence.

Response:

Thank you very much for your comments. Based on your suggestions, we change "4.2 Data sources and descriptions" to "4.2 Data sources", that is, the title is modified, descriptive statistics of variable data are no longer carried out. Table 3 is repositioned in “5.2 Stability test and descriptive statistics of variable data “”in “5. Empirical Analysis”. For details, see the red section.

Thanks again for the reviewer's suggestions.

6. The results of the various statistical tests (Tables 4, 5, and 6) should be placed in the appendix or supplementary material section, rather than within the main body of the paper.

Response:

Thank you very much for your comments. Since this paper adopts "long panel data with variable intercept statically unbalanced", it is necessary to conduct "multicollinearity test" and "stationarity test". To select a suitable estimation method, therefore, "Test results of inter-group heteroscedasticity, intra-group autocorrelation and inter-group correlation" must be carried out. Therefore, these statistical tests are necessary. At the same time, considering that the length of this paper is not very long, we choose to put them in the body. Therefore, please kindly understand our approach.

Thanks again for the reviewer's suggestions.

Reviewer #2:

Comment 1: The introduction is generally fine in it's current state. However, the motivation for this study is completely missing. The contribution of the study is poorly stated and disorganized. It is utterly confusing the purpose of the literature mentioned. The authors should give a clear distinction between this study and existing studies, and provide a clear literature gap.

Response:

Thank you very much for your comments. Based on your suggestions, we have made supplementary revisions to the research contributions in this paper, for details, see the contribution section of "2. Review of Relevant Literature".

Thanks again for the reviewer's suggestions.

Comment 2: The introduction section also did not touch on the main issues in the topic. The authors should conceptualize the terms in the study well and also bring out what other studies have done in this area and what this study seeks to add.

Response:

Thank you very much for your comments. Based on your suggestions, we have expanded and revised the Introduction, for details, see the red part of "1. Introduction".

Thanks again for the reviewer's suggestions.

Comment 3: In the literature review section, the authors should first explain the meaning of commercial health insurance surrender and critically evaluate the literature: Instead of simply summarizing the findings of each study. Discuss any inconsistencies in the existing literature and highlight areas where further research is needed.

Response:

Thank you very much for your comments. Based on your suggestions, we have put the definition and meaning of surrender in the "1. Introduction", highlighted the topic of the article, and revised the "2. Review of Relevant Literature", see the red part of the relevant chapter for specific modifications.

Thanks again for the reviewer's suggestions.

Comment 4: The authors should change the interpretation of results presented in line 327 to 336. Regression and correlation are not the same. Regression shows an effect of one variable on the other and correlation shows linear association.

Response:

Thank you very much for your comments. Based on your suggestions, we have reviewed the relevant data again and believe that the interpretation of the results in lines 327 to 336 is acceptable. The reason is that although regression and correlation are different, they are also related, and correlation analysis is the basis and premise of regression analysis. If there is no correlation, it is meaningless to do regression analysis, that is, regression is based on correlation. Here, we emphasize whether the correlation is positive or negative.

In addition, a lot of literature has been expressed in this way, and we attach the relevant literatures for the review of reviewers. The specific literatures are as follows:

①Wang Min, He Jie, Xu Peng. Ultimate Control Rights and Corporate Fraud: Evidence from China [J]. Emerging Markets Finance and Trade, 2022, 58(4):1206-1213. DOI:10.1080/1540496X.2020.1845647(Page 2)

②Ting Shi, Zang Wenbin, Chen Chen, et al. Income distribution and health: What do we know from Chinese data? [J]. PloS one, 2022, 17(1):e0263008-e0263008. DOI: 10.1371/JOURNAL.PONE.0263008(Page 2)

③Shen Lu, He Guohua, Yan Huan. Research on the Impact of Technological Finance on Financial Stability: Based on the Perspective of High-Quality Economic Growth [J]. Complexity, 2022. DOI: 10.1155/2022/2552520(Page 3)

④Wang Qian, Wang Jun, Gao Feng. Who is more important, parents or children? Economic and environmental factors and health insurance purchase [J]. The North American Journal of Economics and Finance, 2021, 58:101479.DOI: 10.1016/J.NAJEF.2021.101479(Page 2)

However, based on your suggestions, we have made corresponding modifications, specifically, see the red part of "2. Review of Relevant Literature" and the red part of "5.4 Analysis of the empirical results".

Thanks again for the reviewer's suggestions.

Comment 5: The authors should discuss the significance of the coefficients in the regression analysis. It would be useful to provide some economic or practical significance to these findings. Additionally, the authors could compare the findings to existing literature or theoretical expectations to provide a more comprehensive analysis.

Response:

Thank you very much for your comments. Based on your suggestions, we discussed the significance of each coefficient in the regression analysis and compared the research results with existing literatures. For details, see the red part of "5.4 Analysis of the empirical results".

Thanks again for the reviewer's suggestions.

Comment 6: The conclusion of the study is weak, the authors need to indicate the major factors that must be improved to reduce surrender rate in insurance sector in China.

Response:

Thank you very much for your comments. Based on your suggestions, we have given emphasis in the Policy Revelation, as amended in red in "8.2 Policy enlightenments".

Thanks again for the reviewer's suggestions.

Reviewer #3:

1* There is the need to offer justification for focusing on health insurance surrender in China. What is the current situation? what is/are the likely implications if the trend remains same? What are the related policy issues that warrant this study.

Response:

Thank you very much for your comments. Based on your suggestions, we have revised the "Introduction", for details, see the red part of "1. Introduction".

Thanks again for the reviewer's comments.

2* The discussion of the results should be improved. For each KEY variable tell the effect it has on "surrender" and offer possible reasons for the outcome in China. Relate the discussion to the literature and previous empirical studies/findings.

Response:

Thank you very much for your comments. Based on your suggestions, we have revised this, and see the red section of "5.4 Analysis of the empirical results" for details.

Thanks again for the reviewer's comments.

Attachment

Submitted filename: Response to Reviewers.doc

pone.0296695.s003.doc (68KB, doc)

Decision Letter 1

Eric Fosu Oteng-Abayie

10 Nov 2023

PONE-D-23-17007R1A Firm-level Analysis of Chinese Commercial Health Insurance SurrenderPLOS ONE

Dear Dr. Dong,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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PLOS ONE

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Please address the minor concern of Reviewer 2.

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Reviewer's Responses to Questions

Comments to the Author

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Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

**********

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Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: Yes

**********

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Reviewer #1: Yes

Reviewer #2: No

**********

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Reviewer #1: Thank you for your responses to my comments. The subject matter of this article is very important. However, to improve the quality of the paper, I reiterate one of my earlier comments below.

1. The introduction should focus on providing background information and addressing the research gap the study aims to fill. Table 1 should be moved to the empirical analysis section, and a condensed version of Section 3 (Theoretical Analysis and Research Hypothesis) should be integrated into the introduction section.

Reviewer #2: (No Response)

**********

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Reviewer #1: Yes: Kwadwo Arhin

Reviewer #2: Yes: Gideon Mensah

**********

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PLoS One. 2024 Mar 14;19(3):e0296695. doi: 10.1371/journal.pone.0296695.r004

Author response to Decision Letter 1


11 Nov 2023

Response to Reviewers

Reviewer #1:

Thank you for your responses to my comments. The subject matter of this article is very important. However, to improve the quality of the paper, I reiterate one of my earlier comments below.

1. The introduction should focus on providing background information and addressing the research gap the study aims to fill. Table 1 should be moved to the empirical analysis section, and a condensed version of Section 3 (Theoretical Analysis and Research Hypothesis) should be integrated into the introduction section.

Response:

Dear Reviewer Kwadwo Arhin:

Thank you very much for your comments. Based on your suggestion again, we have revised this, specifically see the red part of "1. Question Raised and Research Hypothesis".

Thanks again for your suggestion.

Reviewer #2:

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Response:

Dear Reviewer Gideon Mensah:

Thank you very much for your comments. Based on your suggestion, We have deleted the subdata and provided the master data, as detailed in “Data.xls”.

Thanks again for your suggestion.

Attachment

Submitted filename: Response to Reviewers.doc

pone.0296695.s004.doc (33KB, doc)

Decision Letter 2

Eric Fosu Oteng-Abayie

18 Dec 2023

A Firm-level Analysis of Chinese Commercial Health Insurance Surrender

PONE-D-23-17007R2

Dear Dr. Dong,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Eric Fosu Oteng-Abayie

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The title of section 1 should be changed from "Question Raised and Research Hypothesis" to "Introduction".

Reviewer #2: (No Response)

**********

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If you choose “no”, your identity will remain anonymous but your review may still be made public.

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Reviewer #1: Yes: Kwadwo Arhin

Reviewer #2: Yes: Gideon Mensah

**********

Acceptance letter

Eric Fosu Oteng-Abayie

28 Dec 2023

PONE-D-23-17007R2

PLOS ONE

Dear Dr. Dong,

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PLOS ONE Editorial Office Staff

on behalf of

Dr. Eric Fosu Oteng-Abayie

Academic Editor

PLOS ONE

Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Data

    (XLS)

    pone.0296695.s001.xls (39.5KB, xls)
    S1 File

    (DOC)

    pone.0296695.s002.doc (254.5KB, doc)
    Attachment

    Submitted filename: Response to Reviewers.doc

    pone.0296695.s003.doc (68KB, doc)
    Attachment

    Submitted filename: Response to Reviewers.doc

    pone.0296695.s004.doc (33KB, doc)

    Data Availability Statement

    All relevant data are within the manuscript and its Supporting information files.


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