Item Analysis: Difficulty and Discrimination

Difficulty index, discrimination index and distractor analysis, worked step by step.

Where candidates lose marks on this

1. Reading a high difficulty index as a hard item. High p = easy item. Always.
2. Dividing D by both groups. D = (R_U − R_L)/N_g — one group only.
3. Keeping a negative-D item because its p looks fine. Negative D = discard, whatever the difficulty.
4. Calling Create the top of the ORIGINAL taxonomy. Original tops at Evaluation; Create tops the 2001 revision.
5. Mixing psychomotor counts. Dave 5, Harrow 6, Simpson 7.
6. Marking sentence-completion or word-association as non-projective. They ARE projective; rating scales and situational tests are not.
7. Equating any 5-point scale with Likert. Likert = summated ratings, specifically.
8. NRT/CRT reversal. Percentile rank = norm-referenced; mastery of objectives = criterion-referenced.
9. Placing item analysis after the final form. It precedes and produces the final form.
10. Forgetting that CCE's no-detention basis changed in 2019. Exams in Classes 5 & 8 are now permitted; Delhi detains.

Where this is taught

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