In order for the conclusions reached in Exercise 14.3 to be valid, the conditions of normality, equal variance, and independence must be satisfied. Use the residuals from the fitted model to assess the three conditions. (Refer to the discussion in Section 8.4.)
a. Was there significant evidence of a violation of the normality condition?
b. Was there significant evidence that the variance in reasoning scores was different for the three methods and the control?
c. What is the justification for concluding that the 100 reasoning scores are independent?
d. If the condition of normality and/ or equal variance is violated, what are some alternative methods of analysis?