Journal of the Royal Statistical Society: Series C (Applied Statistics) vol:55 pages:647-676
An item response theory model for dealing with omitted responses in a test is proposed. In this model formulation, non-response does not only depend on an examinee's ability and on item difficulty, but additionally also on 'test speededness'. Using a local-influence-based diagnostic approach, the sensitivity of the model regarding assumptions concerning the drop-out mechanism is explored. The methodology proposed is applied to the Chilean Sistema de Medicion de la Calidad de la Educacion mathematics test case-study.