Box-Cox transformation in NONMEM

From: "Piotrovskij, Vladimir [JanBe]" <VPIOTROV@janbe.jnj.com> Subject: Box-Cox transformation in NONMEM Date: 25 Sep 1998 03:56:48 -0400 Dear NONMEM users, If residuals are highly skewed log transformation of observations and model predictions may help. There is, however, a more general approach in regression called Transform Both Side (TBS) approach (see Carroll & Ruppert 'Transformation and weighting in regression'). Log transformation is a particular case of Box-Cox modified power transformation (y^lambda-1)/lambda for lambda=0. Generally, lambda is a parameter which can be estimated together with other parameters of a regression model. Has anybody experience in applying Box-Cox transformation in NONMEM? Kind regards, Vladimir -------------- Vladimir Piotrovsky Clinical Pharmacokinetics Janssen Research Foundation 2340 Beerse, Belgium e-mail: vpiotrov@janbe.jnj.com