Table 3.

Quantitative studies.

Author/year	Aims	Sample/method	Power calculation/software/analysis tool used	Outcomes	Generalization and confounding factors	Further research
Higgins (2004) [21]	To determine relationship between academic performance, retention, and participation in a peer-tutoring programme.	Purposive sample: 26 at-risk students were offered peer tutoring n = 20 peer tutored; n = 6 in nonpeer tutored group	(i) Power calculation not given. (ii) Fisher's exact test; a two by two bivariate frequency distribution.	Significant relationship between academic performance/retention and participation in a peer-tutoring programme. Attrition rate decreased from 12% to 3%.	Difficult to generalize—no randomization; those who sought peer tutoring may be more motivated to pass. Small sample limited the finding.	Other nursing programs should duplicate peer tutoring for at-risk students in their courses
Hughes et al. (2003) [35]	To investigate effect of an informal peer group experience on baccalaureate nursing students.	Convenience sampling Voluntary selection N = 128	Insufficient power to detect group differences; multiple tools assessed, anxiety, depression, professional socialization, and general self-efficacy.	No significant differences between groups, but increased depression (mean 0.83, SD 0.55) and anxiety (mean 2.40, SD 0.81).	Restricted to two universities. Not generalized. Anecdotal accounts: programme was beneficial maintaining contact with others from group, assisting coping skills.	Need for longitudinal study on nursing at varying stages in course
Lin et al. (2010) [22]	To compare the educational results of peer tutor problem-based learning and conventional teaching in nursing ethics education.	Convenience sampling Randomly assigned to control and intervention groups control = 70, intervention = 72	No power calculation done. Nursing Ethical Discrimination Ability Scale; Learning Satisfaction Survey. Internal consistency reached 0.8 and split-halves reliability was 0.76.	Both methods effective for teaching ethics with PBL (P < 0.01) slightly more effective than conventional lecture (P = 0.020).	Only one university. Limited training of peers, no evaluation of how peers did their job. Teaching materials/teachers may have influenced result. Students used to CLL may prefer this.	Method needs further validation.
Ozturk et al. (2008) [28]	To compare effects of PBL and traditional education on senior undergraduate nursing students' critical thinking dispositions.	Convenience sampling: PBL = 52, CLL = 95	Power calculation not given. California Critical Thinking Disposition Inventory. Independent t-tests for between-group differences.	PBL group showed higher levels of critical thinking than control group (P < 0.01); both groups in medium range for critical thinking (between 240 and 300 on CCTDI).	Two universities, voluntary participation, but good response rates. Generalization could be made with reservations as corroborate previous studies.	Alluded to development of a tool to measure critical thinking that is more specific to nursing.
Rideout et al. (2002) [29]	To compare graduate baccalaureate students in a PBL curriculum with others in a CLL programme.	Convenience sampling: PBL = 75, CLL = 52	No power calculation given. P < 0.01. t-tests, ANOVA for statistical analysis.	No differences in final exam results (P = 0.21) Passed: PBL 93% and CLL 98%)	Restricted to two universities.	Future studies to be longitudinal in design and relying less on self-report measures.
Siu et al. (2005) [30]	To evaluate if nursing students enrolled in PBL programme had higher perceptions of empowerment than those in conventional learning lecture (CLL).	Convenience sampling: PBL = 83, CLL = 70	No power calculation given. Conditions for Learning Effectiveness Questionnaire (CLEQ). Psychological Empowerment Scale, Teaching-Learning Strategies Questionnaire, Clinical Problem-Solving Scale. ANCOVA; Spearman's Rho applied.	PBL experienced greater structural empowerment (P = 0.001). Students taking responsibility for their own learning helped develop effective communication, listening, problem solving, and collaboration skills.	Sample from only two universities. Self-selection and self-reporting questionnaires were a potential problem.	Need for longitudinal investigation and replication with samples from several nursing programs.