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August 2001, Volume 51, Issue 8

Original Article

Problem-Based Learning Variant: Transition phase for a Large Institution

I. Khan  ( Department of Biochemistry, Dow Medical College, Karachi. )
A. Fareed  ( Department of Marketing Statistics, Aga Khan University Hospital, Karachi. )


Objective: To compare students’ test scores and perceptions of problem-based learning (PBL) and lecture-based learning (LBL) by applying a PBL-variant.
Method: For the transition from LBL to PBL, PBL was varied for one discipline only and for a large group of students. Two hundred forty nine second year medical students were taught a topic of Biochemistry by the LBL method and then 141 of these were taught another topic by the PBL-variant. At the conclusion of each topic an MCQ test was given. One week later a 9 item questionnaire was given to the 50 students now attending classes to assess their perceptions of the 2 teaching formats. The test scores of the two methods were compared. Students’ ratings were differentiated by the Wilcoxon Signed-Rank test.
Results: There was no significant difference in the test scores by PBL or LBL, but PBL received significantly higher student ratings (p < 0.05) than LBL in self-study time, library time, number of books and computer consulted, enthusiasth for the topic, group discussion, depth of knowledge and interest taken in the teaching format. But there was no significant difference in students’ ratings of the teacher’s importance in either PBL or LBL.
Conclusion: PBL variant and LBL produced similar MCQ test scores but the former is more conducive to enthusiastic self-study. Thus in the transition phase, PBL may be applied to one discipline and a large group of students without undermining its merits (JPMA 51 :271 :2001).


Dow Medical College is the second oldest Medical College of Pakistan, admitting nearly 480 students annually. The method of teaching is Lecture-based learning (LBL). Recently, the attendance at lectures has fallen sharply. It is assumed that this is because students prefer to study on their own - the immediate goal being to pass the examination. But the Information explosion and the fast pace of change make it necessary to give medical students the scaffolding to become active, self-directed, life-long learners to keep abreast with change1. Adult learning behaviour is also geared to self-directed learning in response to a need.2 So, to make learning more meaningful, clinically oriented and enjoyable3, the administration decided to try Problem-based-learning (PBL).
However, curriculum-wide changes specially in a class size of more than 100 students,3,4 are costly in terms of finances, faculty time, strength of staff and number of rooms required5. International review literature has shown that basic science scores are lower with the PBL method.3,6
To circumvent these problems without sacrificing the advantages of PBL, a PBL-variant was tested in the transition phase using a single discipline-biochemistry, and applying it to the entire class. Large group PBL7 and Single-course PBL5 have been tried before8,9 and have proven to offer potential insight into PBL function. It has been found that facilitator directed learning issues are more beneficial for the students10.
This pilot study was conducted to compare students’ scores and perceptions of the teaching method by LBL and the PBL-variant.


Sample: All second year medical students at Dow Medical College for the year 2000, who were attending lectures.
Intervention - In May 2000, 249 students attending lectures were taught a topic of Biochemistry - “Bio­energetics” by the conventional LBL method, in 10 classes of one hour each. An MCQ test was then given to judge their core knowledge.
By August 2000, the number of students attending the lectures had fallen to 141. They were then taught another Biochemistry topic - “Nucleoprotein metabolism”, by the same teacher, using the PBL-variant method, in 10 classes of one hour each. In the first class, scenario of a “Gout” patient was presented. Active discussion was encouraged. Upon disclosing that his “uric acid” level was higher than normal, the facilitator gently prodded the students towards their knowledge classes of one hour each. In the first class, scenario of a “Gout” patient was presented. Active discussion was encouraged. Upon disclosing that his “uric acid” level was higher than normal, the facilitator gently prodded the students towards their knowledge deficiencies of Nucleoprotein metabolism.
The students identified 8 learning issues. They were asked to divide themselves into eight groups of 15-20 students each, and to select one topic per group. The groups studied on their own from different sources of information. Then, one group made a presentation in each class and the rest of the class were asked to read the topic beforehand and ask them questions. At the end of the presentation, the peers and facilitator both graded the group’s work. In the last class, the whole class pooled in their knowledge to find what was wrong with the patient and how to alleviate it.
Then an MCQ test was given to judge their core knowledge.
One week later only 50 students were attending class. A 9-item questionnaire on an ordinal scale was distributed to check the students’ perception of the two teaching methods (Table 1).

To ensure honest answers, the students were asked not to identify themselves on the questionnaire.
Statistical Analysis
1. Test scores of LBL and PBL were compared. Paired t test was used to detect the difference in the students’ scores11.
2. Since the data for the questionnaire was on an ordinal scale as an alternate for t test on paired differences, Wilcoxon Signed-Rank test was done for the difference in students ratings for PBL and LBL.


As shown in  Table 1 and Figure,

students evaluated PBL significantly higher than LBL (p value <0.05) on 8 of or LBL. the 9 parameters tested - i.e time spent in self-study, number of books consulted, time spent on internet search, time spent in library, interest in method of learning, stimulation for further study, amount of group discussion and depth of knowledge gained.
However, there was no significant difference (p value > 0.05) on the usefulness of the teacher by either PBL or LBL.

Table II shows the marks obtained out of 100 and the nuniber of students who obtained these marks, by both PBL and LBL. The mean grades were almost the same in both systems (71 in PBL against 70 in LBL) and t test for matched samples indicated that there is no significant difference in the scores obtained by students by either PBL or LBL.


This study was conducted over a 6-month period from April to September 2000. The aim of this study was to find if this PBL variant (applied to one discipline only and for a large group) produced results comparable to those obtained by pure PBL. Our results showed that students scored equally well, if not better, with the PBL variant as with LBL. This is consistent with research done on comparison of students’ scores with pure PBL and LBL3,5,8,11. However, some studies have found that PBL scores are better than LBL12,13. Since we were testing this PBL variant in the transition period of changing from LBL to PBL, we were satisfied that the students’ scores did not suffer. But we did find that by this method it took a longer time to complete this same topic than LBL took in the past few years (to classes versus 5 classes for latter).
Students perception of this PBL-variant process were also consistent with the enthusiasm shown for pure PBL by students in other research works done elsewhere3,8,14-16.
Because PBL motivates the students and prepares them for active, self-directed, life-long education as well as the “patient-centered-scenarios” that they will be encountering throughout their lives and because the scores obtained by this method are the same as those with the conventional LBL method, we feel that this PBL variant may be adopted in the transition phase since it has been adapted to counter the effects of a large group size and financial constraints which are the two chief objections worldwide to the changeover from LBL to PBL5. It has already been proposed that PBL should be adapted to suit the requirements3. although some proponents suggest that this should be done only in the transition phase, as it offers less benefits than pure PBL6.
This study had some limitations. Since the sample consisted of all students attending classes, so the sample size for LBL, PBL and the questionnaire were different. Another limitation was the retrospective nature of the students’ ratings - this might have given rise to bias. An interesting follow-up would be to do the same study applying pure PBL and observing if the results are any different from the PBL variant’s results. Then we can judge if a large institution with financial constraints can adopt this PBL variant rather than pure PBL.


The authors wish to acknowledge the support given by Dr. S. Kausar Ali, Associate Professor, Medical Education and Mr. S.M. Raza, Statistician, both at the College of Physicians and Surgeons of Pakistan, who provided technical advice and guidance at all stages of this research.


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