SUMMARYMeasurement of development is often less precise than that of height and weight. Developmental scores are typically based on passing one or more developmental markers, but do not have interval scale so calculating di erences between scores can be nonsensical. Age-speciÿc standardized scores are sometimes used, but fail to have a common metric that allows comparison of developmental scores across age. The goal of this study is to develop a quantitative developmental score (D-score) with improved measurement characteristics. The basic assumption of the D-score is the existence of a common continuous scale for the development. Scores of 2151 children between 0 and 2 years on a Dutch developmental instrument were analysed. Application of the Rasch Model resulted in excellent reliability and satisfactory ÿt. This indicates that the new quantitative D-score succeeds in representing outcomes of the instrument on a common interval scale. Age-conditional reference values for the D-score were derived by means of the LMS method. The deÿnition of the D-scores is not speciÿc to age, so the D-score of a measured person can be compared to the D-score of another person of a di erent age. Di erence scores between sessions can be used to evaluate developmental velocity on the individual level. To our knowledge this is the ÿrst developmental scale for children with such properties.

Developmental indicators that are used for routine measurement in The Netherlands are usually chosen to optimally identify delayed children. Measurements on the majority of children without problems are therefore quite imprecise. This study explores the use of computerized adaptive testing (CAT) to monitor the development of young children. CAT is expected to improve the measurement precision of the instrument. We do two simulation studies - one with real data and one with simulated data - to evaluate the usefulness of CAT. It is shown that CAT selects developmental indicators that maximally match the individual child, so that all children can be measured to the same precision.

Some PCH professionals are more likely to identify psychosocial problems than others, independently from parent-reported problems or other risk indicators.

BackgroundQuestionnaires used by health services to identify children with psychosocial problems are often rather short. The psychometric properties of such short questionnaires are mostly less than needed for an accurate distinction between children with and without problems. We aimed to assess whether a short Computerized Adaptive Test (CAT) can overcome the weaknesses of short written questionnaires when identifying children with psychosocial problems.MethodWe used a Dutch national data set obtained from parents of children invited for a routine health examination by Preventive Child Healthcare with 205 items on behavioral and emotional problems (n = 2,041, response 84%). In a random subsample we determined which items met the requirements of an Item Response Theory (IRT) model to a sufficient degree. Using those items, item parameters necessary for a CAT were calculated and a cut-off point was defined. In the remaining subsample we determined the validity and efficiency of a Computerized Adaptive Test using simulation techniques, with current treatment status and a clinical score on the Total Problem Scale (TPS) of the Child Behavior Checklist as criteria.ResultsOut of 205 items available 190 sufficiently met the criteria of the underlying IRT model. For 90% of the children a score above or below cut-off point could be determined with 95% accuracy. The mean number of items needed to achieve this was 12. Sensitivity and specificity with the TPS as a criterion were 0.89 and 0.91, respectively.ConclusionAn IRT-based CAT is a very promising option for the identification of psychosocial problems in children, as it can lead to an efficient, yet high-quality identification. The results of our simulation study need to be replicated in a real-life administration of this CAT.

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