- Question 2 50 The Rats Dataset In R Is A Dataset That Was Collected As Part Of An Investigation To Eliminate The Effec 1 (145.34 KiB) Viewed 117 times
Question 2 [50] The rats dataset in R is a dataset that was collected as part of an investigation to eliminate the effect of certain toxic agents on rats. A total of 48 rats were randomly assigned to one of the three poisons and one of the four treatments. Thereafter the survival time of the rats was measured in tens of hours. Use R-software to answer the questions that follow. Present or attach the R codes and outputs used to answer the questions. 2.1 Write the appropriate model for the analysis of these data. Explaining each term in the model and the assumptions made about these terms. (8) 2 STA3701/014/3/2021 2.2 Construct an analysis of variance table needed to analyse these data using R software. In- clude a column of expected mean squares. (6) 2.3 Use the ANOVA table to test whether type of poison, treatments, or their interaction contribute significantly to the variation in survival times of the rats using 10% level of significance. For the tests, provide the null and alternative hypotheses, critical regions (or rejection regions), test statistics and your conclusions. (15) 2.4 Check the assumptions on a two-way ANOVA model you fitted in part (b) for these data. If the assumptions are satisfied, then conduct all possible hypotheses and discuss your conclu- sions. (10) 2.5 Estimate significant variance components by providing point estimates and by calculating 95% confidence intervals. (6) 2.6 Draw an interaction plot for the data. Does your interaction plot support the conclusion of your hypothesis test in part 2.3 concerning interaction? Explain. (5)