Does the EDI Measure School Readiness in the Same Way Across Different Groups of Children?

Abstract

The present study investigates whether the Early Development Instrument (Offord & Janus, 1999 Offord, D., Janus, M. (1999). Early Development Instrument. A population-based measure for communities (2004/05 version). Retrieved November 20, 2006 www.offordcentre.com/readiness/EDI_viewonly.html [Google Scholar]) measures school readiness similarly across different groups of children. We employ ordinal logistic regression to investigate differential item functioning, a method of examining measurement bias. For 40,000 children, our analysis compares groups according to gender, English-as-a-second-language (ESL) status, and Aboriginal status. Our results indicate no systematic measurement differences regarding Aboriginal status and gender, except for 1 item on which boys are more likely than girls to be rated as physically aggressive by Kindergarten teachers. In contrast, ESL children systematically receive lower ratings on items of the language and communication domains—as expected by definition of ESL status—but not within the physical, social, and emotional domains. We discuss how our results fit with child development research and the purpose of the Early Development Instrument, thus supporting its validity.