Why should you always carry out a residual analysis as part of a regression model?

a.

Residual analysis gives a better estimation of the variability of the independent variable.

b.

Residual analysis helps with estimation of the intercept and the slope of the regression line.

c.

Unless a residual analysis is undertaken, you will not know whether the model fit is appropriate for the data. In addition, residual analysis can be used to check whether the assumptions of regression have been seriously violated.