The Psychometric Properties of the Early Development Instrument: A Rasch Analysis Based on Swedish Pilot Data

The Early Development Instrument (EDI) is a population measure and an indicator of children’s developmental health before entering the school system. EDI-Sweden was translated and adapted from EDI-Canada. In 2011 a pilot study was conducted, as a first step of the preparations for nationwide implementation of EDI in Sweden. The purpose of the study is to analyse the psychometric properties of EDI-Sweden. Data about 116 5-year-old children were collected at ten preschools in two municipalities. EDI consists of 104 core items in five domains: physical health and well-being, social competence, emotional maturity, language and cognitive development, communication skills and general knowledge. Preschool teachers completed a web based questionnaire for each child. The data were analysed using the unidimensional Rasch model. With exception for the domain of physical health and well-being the Rasch analysis showed satisfying psychometric properties of EDI after removal of some misfitting items. In these four domains no items showed disordered thresholds and the reliability was good, indicated by person separation index values of 0.73 or higher. Tentative analyses of Differential Item Functioning (DIF) showed that some items didn’t work invariantly across genders, suggesting that the DIF-items should be split into gender specific items. Due to the relatively small sample size the results can’t provide definite answers but tentative indications of the psychometric properties of the EDI-Sweden. As a whole the Rasch analysis provides ground for cautious optimism for large scale assessment of EDI-Sweden enabling more thorough and finer level analysis of the instrument. Copyright Springer Science+Business Media Dordrecht 2014