A comparison of goodness of fit tests for age‐related reference ranges

Abstract

Age‐related reference ranges based on cubic spline or kernel‐based smoothing methods lack a parametric framework with which to assess goodness of fit, as the distribution of the log‐likelihood ratio comparing models with different degrees of smoothing is not known in general. Several methods have been proposed to assess goodness of fit in this case: Healy's grid test, Royston's Q tests and van Buuren's worm plot. Here we compare the performance of the various methods, including an extension of the Q tests, and show how they can be used, with other information including the appearance of the fitted curves, to inform the choice of model for age‐related reference ranges of height and weight in a large Dutch data set. Copyright © 2004 John Wiley & Sons, Ltd.