A study by Rikkers et al. (1978) involved a prospective randomized surgical trial that compared cirrhotic patients
Question:
Pre- and postoperative maximal rate of urea synthesis level (MRUS) by group
a. Decide whether each of the factors Group (Selective Shunt versus Nonselective Shunt) and Time (PreOp versus PostOp) should be considered as a fixed or as a random factor. Explain.
b. State a subject-specific scalar model for analyzing the above data, and specify the assumptions typically made about the random effects (including the error term) in the model.
c. State the subject-specific matrix model that corresponds to the model you provided in your answer to part (b).
d. State the null hypothesis that there is no significant effect of the factor Group in terms of a statement about parameters in your model given in part (b). What other null hypothesis should be tested prior to testing whether there is a significant effect of Group?
e. Based on a comparison of sample means, does there appear to be a meaningful difference in the change in liver function between the two groups? Explain.
f. Below are given computer results for a repeated measures analysis of these data. Based on these results, is there a significant effect of the factor Group? Explain by describing the F statistic, its degrees of freedom, and its P-value appropriate for these data.
g. Use the output to test whether there is a significant random effect for Subjects.
Step by Step Answer:
Applied Regression Analysis and Other Multivariable Methods
ISBN: 978-1285051086
5th edition
Authors: David G. Kleinbaum, Lawrence L. Kupper, Azhar Nizam, Eli S. Rosenberg