AW: Modeling of inter study variability (ISV) as a third random e ffec t level

From: "Harnisch, Lutz, HMR/DE" <Lutz.Harnisch@hmrag.com> Subject: AW: Modeling of inter study variability (ISV) as a third random e ffec t level Date: Mon, 31 May 1999 18:36:13 +0200 Dear Pascal, Thank you very much for your ideas. We were puzzled about this topic already at PAGE in Wuppertal. In our pooled phase I analysis, the maximum number of individuals within a study was larger than 20 subjects/study, however, the number of studies were below 20. Therefore, the introduction of more than 20 IOV corresponding to the maximum number of individuals might extent the limits in NONMEM, taking also into account that 20 IOVs for each parameter in the PK model are required, probably. Therefore we decided to take only a single THETA for each study, and to summarize them in a second stage. But what do you think about taking a small random sample of individuals from each study (around 5 IOVs), and apply your approach? regards Lutz