Correct option is B
Item Discriminability refers to how well a test item differentiates between high-scoring and low-scoring individuals on the overall test. It helps determine whether those who perform well on a particular item also tend to perform well on the whole test.
-A highly discriminating item means that high-achieving test-takers are more likely to answer it correctly, while low-achieving test-takers are more likely to get it wrong.
-It is measured using item-total correlation or discrimination indices (e.g., Point-Biserial Correlation, Discrimination Index (D)).
-It is essential for test validity and ensures that test items contribute effectively to assessing the intended ability.
Information Booster:
-Item Discriminability is crucial for test standardization and helps in removing poor-quality items.
-It is often measured using Point-Biserial Correlation and Discrimination Index (D).
-Items with high discriminability improve the test’s reliability and validity.
-A good test item should have a moderate level of difficulty and high discrimination power.
-Items with low discrimination do not help in distinguishing between high- and low-performing individuals and should be revised.
-Classical Test Theory (CTT) and Item Response Theory (IRT) use item discrimination to refine tests.
Additional Information:
Item Difficulty (Option 1 )
Measures how easy or hard an item is but does not indicate whether high scorers perform better than low scorers.
Example: If most test-takers answer a question correctly, it has low difficulty but may not be a good discriminator.
Item Reliability (Option 3)
Refers to the consistency of an item over multiple test administrations.
A reliable item may still fail to differentiate high and low scorers.
Item Validity (Option 4 )
Indicates whether the item measures what it is supposed to measure, but not whether it differentiates between test-takers effectively.
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