Itemianalyysillä

Itemianalyysillä, often translated as item analysis, is a statistical method used in psychometrics and educational measurement to evaluate the quality of individual items within a test or questionnaire. It helps in determining whether an item is functioning effectively and contributing appropriately to the overall measurement of the intended construct.

The primary goals of item analysis are to identify items that are too easy or too difficult, and items that do not discriminate well between individuals with high and low levels of the trait being measured. This is typically achieved by examining item difficulty and item discrimination.

Item difficulty refers to the proportion of respondents who answer an item correctly. An item that is answered correctly by almost everyone is considered too easy, while an item answered correctly by very few is considered too difficult. Both extremes can reduce the item's effectiveness.

Item discrimination measures how well an item differentiates between individuals who score high on the total test and those who score low. A good discriminating item will be answered correctly more often by high-scoring individuals than by low-scoring individuals.

Information derived from item analysis is crucial for test construction and revision. It allows researchers and educators to refine their assessment tools by removing or modifying poorly performing items, thereby improving the reliability and validity of the measurement instrument. This process ensures that the test accurately measures what it is intended to measure.