RE: WRES AND OUTLIER IDENTIFICATION/EXCLUSION

From: "Mats Karlsson" mats.karlsson@farmbio.uu.se Subject: RE: [NMusers] WRES AND OUTLIER IDENTIFICATION/EXCLUSION Date: Tue, 26 Sep 2006 23:44:00 +0200 Hi Chuanpu, You wrote "As Mats suggested, most of the time outliers are model-dependent; i.e., outliers occurred because the appropriate model wasn't or couldn't be fitted." Actually, I don't think I said this. My general impression, which doesn't particularly influence how I handle these cases, is that once we've done a good job on the modeling, the remaining outliers are most likely errors in data, which would occur under any reasonable model. Further, you wrote: "This can only be assessed by analyzing data in two ways, including and excluding the outliers." Although I think that such contrasting analyses can be of great help to understand the impact of anomalous data, my point was the opposite, you don't necessarily have to do these contrasting analyses if you use a model that is more robust to outliers/errors. Best regards, Mats Mats Karlsson, PhD Professor of Pharmacometrics Div. of Pharmacokinetics and Drug Therapy Dept. of Pharmaceutical Biosciences Faculty of Pharmacy Uppsala University Box 591 SE-751 24 Uppsala Sweden phone +46 18 471 4105 fax +46 18 471 4003 mats.karlsson@farmbio.uu.se