Abstract
To adapt home intervention processes to the needs of a child, a correct overview of skills that the child masters is necessary. The Portage Program, a home intervention program for families with children from 0 to 6 years of age with special educational needs, uses a checklist to assess the developmental skills that the child masters (S. M. Bluma, M. S. Shearer, A. H. Frohman, & J. M. Hilliard, 1976). Although a correct order of the items of the checklist is important for the planning of the home intervention process, the order of the items has never been empirically validated (B. F. Van der Meulen, W. G. Sipma, & C. E. J. Feenstra, 1993). This article describes a study on the scalability and item order of the revised checklist of the Dutch version of the Portage Program using Item Response Theory Modeling. The items of the checklist were administered to a sample of 736 families by using an incomplete data collection design. Results showed that it was possible to find a marginally or reasonably fitting scale for all areas of the checklist. Reordering of the items was necessary to get a correct overview of skills that the child masters. Our results have implications for future research into the use of the original checklist in other countries.