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Dept. of Biostatistics
and Epidemiology at the
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Reading:
Problems: 1. A clinical trial is described by Searle et al in Example 2, p8. The trial is conducted using 24 executives, and involves a placebo and 3 different medications. We assume that no measures were made on subjects before treatment, and that the only available data are after treatment measures. The potentially observable responses from this trial are given below. This assignment focuses on this example. The data were created by the SAS program D40P1.SAS. These data are stored in the ASCII file hw1a.txt . A. Use the notation from the first reading to define the population(s), factors, and parameters in the population. Also define parameters corresponding to an average of population means, and a factor level effect, defined as a deviation from the average of population means. B. Evaluate the values of the parameters in the populations corresponding to the mean and variance. Also evaluate parameters corresponding to the average of population means, and factor level effect parameters. Verify that the factor level effect parameters sum to zero. C. Suppose a study is conducted as described by Searle et al. with only "after" treatment measures. Describe a random sampling plan that would correspond to the study design. D. Define indices, random variables, and a model that represents response for a randomly selected subject. E. Conduct the experiment according to the sampling plan that is described in D. Describe how you conducted the experiment, and list the realized values for random variables that you obtain in four columns, with one column representing responses for each factor level. F. Can you tell in your sample whether there is a subject by treatment interaction? Why or why not? G. In the potentially observable population in Table 1., can you tell whether there is a subject by treatment interaction. Why or why not?
Last Update: 2/2/99 Comments: Ed Stanek Email: stanek@schoolph.umass.edu \ed\web\be740\webready\hw1.html |
