A meta-analysis by Dochy, Segers, Van den Bossche, and Gijbels (2003) examines the effects of problem-based learning (PBL) on knowledge and skills in tertiary education. The study analyzed 43 empirical studies conducted in real-life classrooms. The results show a robust positive effect of PBL on students' skills, with both vote counts and combined effect sizes indicating significant improvements. However, the effect on knowledge is less consistent, with a slightly negative combined effect size, though this is heavily influenced by two outlier studies. The vote count does not reach statistical significance for knowledge outcomes. The analysis identified several moderators of PBL effects. Methodological factors, such as research design and scope of implementation, influenced the results. For instance, randomized studies showed less negative effects on knowledge, while studies with a broader scope (e.g., curriculum-wide) showed more positive effects. Student expertise level also played a role, with significant variations in effect sizes for both knowledge and skills. The negative effect on knowledge in the first two years diminished over time, suggesting that PBL helps students apply knowledge more effectively in the long term. The retention period had a notable impact on knowledge retention, with PBL students remembering more of what they learned, even if they had slightly less knowledge. For skills, the effect was consistent and lasting, regardless of the retention period. The type of assessment method also influenced outcomes, with tests that assessed knowledge application showing stronger positive effects of PBL. Instruments like performance-based testing and case-based assessments were particularly effective in measuring PBL's impact on skills. Overall, the meta-analysis concludes that PBL has a robust positive effect on students' skills, with mixed but generally positive effects on knowledge. The results suggest that PBL is effective in fostering skills and knowledge application, though its impact on knowledge may vary depending on factors like student expertise, assessment methods, and the scope of implementation. The study highlights the importance of considering these moderators when evaluating the effectiveness of PBL in educational settings.A meta-analysis by Dochy, Segers, Van den Bossche, and Gijbels (2003) examines the effects of problem-based learning (PBL) on knowledge and skills in tertiary education. The study analyzed 43 empirical studies conducted in real-life classrooms. The results show a robust positive effect of PBL on students' skills, with both vote counts and combined effect sizes indicating significant improvements. However, the effect on knowledge is less consistent, with a slightly negative combined effect size, though this is heavily influenced by two outlier studies. The vote count does not reach statistical significance for knowledge outcomes. The analysis identified several moderators of PBL effects. Methodological factors, such as research design and scope of implementation, influenced the results. For instance, randomized studies showed less negative effects on knowledge, while studies with a broader scope (e.g., curriculum-wide) showed more positive effects. Student expertise level also played a role, with significant variations in effect sizes for both knowledge and skills. The negative effect on knowledge in the first two years diminished over time, suggesting that PBL helps students apply knowledge more effectively in the long term. The retention period had a notable impact on knowledge retention, with PBL students remembering more of what they learned, even if they had slightly less knowledge. For skills, the effect was consistent and lasting, regardless of the retention period. The type of assessment method also influenced outcomes, with tests that assessed knowledge application showing stronger positive effects of PBL. Instruments like performance-based testing and case-based assessments were particularly effective in measuring PBL's impact on skills. Overall, the meta-analysis concludes that PBL has a robust positive effect on students' skills, with mixed but generally positive effects on knowledge. The results suggest that PBL is effective in fostering skills and knowledge application, though its impact on knowledge may vary depending on factors like student expertise, assessment methods, and the scope of implementation. The study highlights the importance of considering these moderators when evaluating the effectiveness of PBL in educational settings.