Empirical Analysis of Item Difficulty and Discrimination Indices of Senior School Certificate Multiple Choice Biology Tests

This study empirically analyzed the item difficulty and discrimination indices of senior school certificate examination SSCE multiple choice biology tests used by West African Examinations Council and National Examinations Council in Nigeria. Sample for the study consisted of 1450 Senior Secondary Three students drawn from 20 randomly selected secondary schools. Item by item analysis was used for obtaining difficulty and discrimination indices. Findings from the study showed that 2008 SSCE Biology multiple choice test had mean difficulty index of 0.42 and slightly higher than NECO Biology multiple choice test with mean difficulty index of 0.40 and 2008 SSCE in Biology had a discriminating power of 0.43 and higher than NECO with mean discriminating power of 0.39. It was recommended that 4 option items in multiple choice Biology tests should be encouraged but if 5 options items should be used more attention should be given to psychometric properties of tests.