CWRES/WRES comparisons can also indicate if the FOCE estimation method will improve the results of an FO model fit to data. In contrast, in certain circumstances, the WRES have distributions that greatly deviate from the expected, falsely indicating model misspecification. Using real and simulated data the CWRES distributions behave as theoretically expected under the correct model. We present a new diagnostic tool, the conditional weighted residuals (CWRES), which are calculated based on the FOCE approximation.ĬWRES are calculated as the FOCE approximated difference between an individual's data and the model prediction of that data divided by the root of the covariance of the data given the model.
Utilizing WRES with the FOCE method may lead to misguided model development/evaluation. However, the weighted residuals (WRES), a common diagnostic tool used to test for model misspecification, are calculated using the FO approximation. Population model analyses have shifted from using the first order (FO) to the first-order with conditional estimation (FOCE) approximation to the true model.
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