Validation of multiple true or false (MTF) questions and their usefulness in assessment in an undergraduate medical programme

Objective: To find out difficulty index (P) and discrimination index (D) of the items - Multiple True or False (MTF) questions- set for the examinations conducted by constituent departments of a medical college, namely: anatomy, physiology, biochemistry, pathology, pharmacology and microbiology. Methods: Scores obtained by students of first year MBBS (March 2010 batch) in anatomy, physiology, biochemistry and second year students (March 2009 batch) in pathology, pharmacology and microbiology were taken. MTF component of the examination of block 1, 2, 3 and 4 were considered. Difficulty index (P) and discrimination index (D) of MTF component of block 1, 2, 3 and 4 were analyzed using Microsoft excel. Correlations of MTF and essay scores of the examinations were also performed. Results: The average easy questions(P ≥ 75%) were 48%, 65% and 51% & percentage of average difficult questions (P ≤ 25%) were 3%, 1% and 2% in anatomy, physiology and biochemistry respectively. Anatomy, physiology and biochemistry had 71%, 56% and 67% of questions with discrimination index D ≥ 0.2. The average easy questions were 64%, 51% and 46% & percentage of average difficult questions was 3%, 3% & 4% in pathology, pharmacology and microbiology respectively. Pathology, pharmacology and microbiology had 40%, 51% and 50% of questions with discrimination index D ≥ 0.2. The essay and MTF scores of each subject showed strong and significant correlations. Conclusion: The difficulty index obtained from the analysis shows that the questions were easy for the students. However, the study shows that about 50% of the questions were capable of discriminating students with higher ability from those with lower ability (D ≥ 0.2).