Intersection point k0 of item difficulty and discriminating curves provides a data-driven item-deletion criterion¶
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Evidence · 1 study · theoreticalr2·q2
Currency · newest study 2021 · checked against its sources 2026-10-20 (automated, 1 of 1 entry) · not reviewed by a person
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q2 i? As k increases, the item difficulty curve increases and the percentage item discriminating curve decreases; their intersection point k0 defines an acceptance region (k0 ± 2SD) for deciding which items to delete. → Chakrabartty 2021
Evidence¶
Chakrabartty 2021¶
Chakrabartty, S. N. (2021). Assessment of item and test parameters: Cosine similarity approach. International Journal of Psychology and Educational Studies, 8(3), 28-38. https://dx.doi.org/10.52380/ijpes.2021.8.3.190
q2 · i? · theoretical · r2
Figure 1 plots item difficulty values and percentage discriminating values against k for the 50-item test; the curves intersect at k0 = 368, where item difficulty is 0.40395 and percentage item discriminating is 0.40245. Acceptance-region methods discarded item no. 40 only.
"Clearly, as k increases, item difficulty curve increases and percentage item discriminating curve decreases. The two curves cut at a point ( 𝑘0)= 368."
Discussion¶
Related Claims¶
- Item discriminating value as coefficient of variation decreases monotonically as number of correct answers increases, giving a negative difficulty–discrimination relationship — related
- Point-biserial item-total correlation is negatively related to test discriminating value and can be expressed via item and test difficulty and discrimination parameters — related
- Statistical item selection that maximizes norm-referenced discrimination undermines criterion-referenced test definitions — related
- Test difficulty value defined as ratio of observed to maximum score vector length times cosine of their angle equals test mean divided by number of items — related
- Learned difficulty parameters show a moderate positive correlation with empirical KC difficulty on QATD2k — related
- Nonintervention (observational) studies in educational psychology are producing recommendations for practice at increasing rates — related
Page metadata
| Field | Value |
|---|---|
type |
claim |
id |
k0-intersection-item-deletion-criterion |
title |
Intersection point k0 of item difficulty and discriminating curves provides a data-driven item-deletion criterion |
description |
Intersection point k0 of item difficulty and discriminating curves provides a data-driven item-deletion criterion |
status |
review |
evidence_strength |
moderate |
newest_evidence |
2021 |
source_checked |
2026-10-20 |
generated |
by process:wiki-ingest on 2026-09-25 |
trust |
unverified — no one has confirmed this page's content |
sources |
1 — chakrabartty-2021 |
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