Question

If a diagnostic plot shows residuals (i.e., error terms) get wider as the value of the predicted value (x) increases (i.e., an “open megaphone” shape), then this is indicative of a violation of which linear regression assumption?

Select one:

a. No outliers

b. Analysis of variance

c. Constant variance

Answer 1

c. constant variance

Heteroscedasticity produces a distinctive fan or cone shape in residual plots. To check for heteroscedasticity, you need to assess the residuals by fitted value plots specifically. Typically, the telltale pattern for heteroscedasticity is that as the fitted values increases, the variance of the residuals also increases.