Item Pool Maintenance in the Presence of Item Parameter Drift

Differential linear drift of item location parameters over a 10 ‐year period is demonstrated in data from the College Board Physics Achievement Test. The relative direction of drift is associated with the content of the items and reflects changing emphasis in the physics curricula of American secondary schools. No evidence of drift of discriminating power parameters was found. Statistical procedures for detecting, estimating, and accounting for item parameter drift in item pools for long‐term testing programs are proposed