Psychometric properties and contextual appropriateness of the German version of the Early Development Instrument

BACKGROUND: Assessing the early development of children at a population level in educational settings, may be useful for public health and policy decision making. In this study, we evaluated the psychometric properties and the contextual appropriateness of a German language version of the Early Development Instrument (EDI), a survey-based instrument originally developed in Canada, which assesses developmental vulnerability for children in preschool settings. METHODS: Sixty preschool teachers from six preschool organizations (22% of organizations contacted) in three cities in southwest Germany participated. They administered a German version of the EDI (GEDI) to 225 children (51% of eligible children). We assessed internal consistency, test-retest and interrater reliability. Preschool teachers assisted in determining face-validity by reviewing item coverage and comprehensibility. Exploratory factor analysis (EFA) was used to evaluate convergent validity. Concurrent validity was measured using correlations and agreements (Bland-Altman plots) between GEDI and other validated instrument scores. Additionally, we compared associations between GEDI domain scores and sociodemographic characteristics with similar associations in EDI studies worldwide. RESULTS: GEDI domains showed good to excellent internal consistency (0.73 < α > 0.99) and moderate to good test-retest and interrater reliability (0.50 to 0.81 and 0.48 to 0.71, respectively [p-value < 0.05]). Face validity was considered acceptable. EFA showed a factor structure similar to the original EDI. Correlations (range: 0.32 to 0.67) and agreements between GEDI scores and other German language instruments suggested good external reliability. Scoring within the lowest 10th percentile was strongly associated with age. CONCLUSIONS: Our psychometric assessment suggests good reliability and consistency of the GEDI. Differences in the age distribution of children, pedagogical objectives and educational system features of German preschools require future work to determine score thresholds indicative of vulnerability. Aside from dropping selected items from the original EDI that were inconsistent with features of the German educational system, the distribution of values in the language and cognitive development domain also suggested that context-specific cut-offs must be established for the German version. Such efforts are needed to account for relevant contextual differences between the educational systems.