Item Analysis
25 min
Simple Explanation
Item analysis is the statistical evaluation of assessment item performance after delivery. It uses metrics like facility, discrimination, and distractor analysis to improve future assessments.
Professional Definition
Item analysis involves statistical evaluation using facility index (difficulty), discrimination index (how well items separate able from less able learners), and distractor analysis (for MCQs). It informs improvement.
Explain It to a 10-Year-Old
Item analysis is like reviewing game footage after a match. You look at which plays worked (items that performed well), which did not (items too easy or hard), and adjust your strategy for next time.
Why It Matters
Without item analysis, you never learn which items work and which do not. Poor items are reused, good items discarded, and assessment quality stagnates. Item analysis drives continuous improvement.
Where It Fits in the Process
This topic belongs to Delivery & Evaluation in the assessment development journey.
Step-by-Step Process
Per-item, per-learner responses
Proportion answering correctly
Do high-ability learners get it right more than low-ability?
Is each distractor attracting some learners?
Revise, retain, or retire each item
Worked Example
Facility: 0.85 (85% correct) — may be too easy
Discrimination: 0.25 — low discrimination; does not separate able/less able well
Distractor A: Selected by 2% — implausible; needs rewriting
Distractor C: Selected by 8% — plausible but not diagnostic
Distractor D: Selected by 5% — acceptable
Recommendation: Review stem for higher demand. Rewrite distractor A.
Common Mistakes
| Mistake | Problem | Better Approach |
|---|---|---|
| Interpreting facility alone | A facility of 0.5 could be good discriminating or poor ambiguous | Always review facility alongside discrimination |
| Ignoring distractor analysis | Implausible distractors reduce effective options | Review and rewrite distractors attracting fewer than 5% of learners |
Checklist
of 4 complete
Interview Connection
You may be asked about this topic in assessment developer interviews.
Practice Interview QuestionsKnowledge Check (3 Questions)
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Summary
- Item analysis evaluates item performance post-delivery
- Facility index = proportion correct (difficulty)
- Discrimination index = how well item separates ability levels
- Distractor analysis reveals implausible or non-functioning options
- Item analysis drives continuous improvement