RE: WRES AND OUTLIER IDENTIFICATION/EXCLUSION

From: "Kowalski, Ken" Ken.Kowalski@pfizer.com Subject: RE: [NMusers] WRES AND OUTLIER IDENTIFICATION/EXCLUSION Date: Mon, 2 Oct 2006 16:31:43 -0400 Nick, Sorry for the confusion. Mats' suggestion to identify subjects with at least one outlier observation (data point) via the $MIX code combined with the residual error mixture model should not be confused with the distinct but separate issue of "outlier subjects". Note that an "outlier subject" whose individual curve deviates substantially from the typical individual curve may not have any individual data point outliers. That is, conditional on the subject's ETA values, the deviations from IPRED may not be extreme (i.e., no extreme IWRES values). We are not dealing with outlier subjects whose curves may represent extreme deviations from PRED (e.g., extreme ETA values) but whose individual observations are reasonably consistent within the individual. Ken