The following values of a response Y were obtained for three settings of a categorical predictor…
The following values of a response Y were obtained for three settings of a categorical predictor A
Suppose we assume the normal regression model for these data with one categorical predictor.
(a) Produce a side-by-side boxplot for the data. (b) Plot the standardized residuals against A (if you are using a computer for your calculations, also produce a normal probability plot of the standardized residuals) Does this give you grounds for concern that the model assumptions are incorrect?
(c) Carry out a one-way ANOVA to test for any difference among the conditional means of Y given A
(d) If warranted, construct 0.95-confidence intervals for the differences between the means and summarize your finding