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Unformatted text preview: Lecture 13 More Practice With Bayesian Data Analysis Example 1 : A Bioassay Experiment In the development of drugs and other chemical compounds, acute toxicity tests or bioas say experiments are commonly performed on animals. Such experiments proceed by administering various dose levels of the compound to batches of animals. The animals responses are typically characterized by a dichotomous outcome: for example, alive or dead, tumor or no tumor. An experiment of this kind gives rise to the data shown below where x i represents the i th of N = 4 dose levels (measured on the log scale) given to n i animals, of which y i subsequently respond with positive outcome. Two hundred animals were tested, 50 at each of the four dose levels. Dose, x i Number of Number of (log g/ml) animals, n i deaths, y i0.863 500.296 50 80.053 50 32 0.727 50 50 The Standard Logistic Regression Model The standard logistic regression model for these data is y i  p i Binomial( n i ,p i ) y i  p i independent i = 1 , 2 , 3 , 4 logit( p i ) = + x i We can check if there is a linear trend between x and the sample logits. Since a linear trend seems appropriate, we fit the model....
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This note was uploaded on 02/07/2010 for the course STATS 620202 taught by Professor R during the Two '09 term at University of Melbourne.
 Two '09
 R
 Statistics

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