Itemanalyses

Itemanalyses refers to the examination of individual items within a test, questionnaire, or assessment instrument to evaluate their performance and contribution to overall measurement goals. Typically used in educational testing, psychological measurement, and survey research, item analyses help developers refine items, improve reliability, and detect biased or ineffective questions.

Common approaches include classical test theory (CTT) and item response theory (IRT). In CTT, key statistics are item difficulty (proportion of correct responses for achievement items), item discrimination (correlation between item score and total test score, often using point-biserial or discrimination index), and distractor analysis for multiple-choice items. These metrics inform which items are too easy or too hard, fail to distinguish between high- and low-performing examinees, or contain nonfunctional distractors. IRT models estimate item parameters such as difficulty, discrimination, and guessing, and generate item characteristic curves and information functions that describe how well items measure across ability levels.

Practical applications include test development, form assembly, score scale construction, and psychometric research. Itemanalyses also support fairness reviews by identifying differential item functioning across demographic groups.

Limitations include dependence on sample characteristics, the need for sufficient sample size and representative populations, and the fact that statistical item performance should be interpreted alongside content review and subject-matter considerations. When used iteratively with qualitative review, itemanalyses are a central tool for creating valid, reliable assessment instruments.