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Abstract Details

Activity Number: 522
Type: Contributed
Date/Time: Wednesday, August 1, 2012 : 10:30 AM to 12:20 PM
Sponsor: Biopharmaceutical Section
Abstract - #306812
Title: On the Problem of Identifiabilityof the EMAX Model
Author(s): Ha Nguyen*+ and Birol Emir and Javier Cabrera and Feihan Lu
Companies: Pfizer Inc. and Pfizer Inc. and Rutgers University and New York University
Address: 235 42nd St., New York, NY, 10017, United States
Keywords: Emax ; Maximum Likelihood ; Dose Response

The EMAX model is a standard dose-response model in many clinical studies. One of the difficulties we face when fitting an EMAX model is the frequent lack of convergence of the MLE which is often caused by a poor study design in the sense that the dose range used is too small. In this talk, we will present an estimation procedure which determines when there is enough evidence for estimating the EMAX parameter or when there is not. One element of the procedure is the incorporation of data visualization diagnostics to verify the validity of each step of the methods. In addition, we performed extensive simulations to understand better the issues with the convergence of the models and the accuracy of the parameter estimates, and provide a set of guidelines on sample size related to signal to noise ratio and dose ranges that are useful to design new experiments.

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