Discriminointikyvyn

Discriminointikyvyn, often translated as discriminative ability or discrimination index, is a concept used primarily in psychometrics and educational assessment to evaluate how well a test item or a question distinguishes between individuals who have high overall ability and those who have low overall ability. It is a measure of the item's effectiveness in separating these two groups.

To calculate discriminointikyvyn, the total score on a test is typically used as a criterion. Individuals are divided into two groups, usually the top 27% and the bottom 27% of test-takers based on their total scores. Then, the proportion of individuals in the high-scoring group who answered the specific item correctly is compared to the proportion of individuals in the low-scoring group who answered the same item correctly. A higher proportion of correct answers in the high-scoring group compared to the low-scoring group indicates good discriminative ability for that item.

Items with high discriminointikyvyn are considered good items because they effectively identify individuals with higher knowledge or skill in the subject matter. Conversely, items with low or negative discriminointikyvyn may be problematic. A negative value suggests that more low-scoring individuals answered the item correctly than high-scoring individuals, which could indicate an error in the item or a misunderstanding of the test's purpose. These items might be revised or removed from future test administrations.