Which of the following is not a requirement for regression analysis?
a: outliers can have a strong effect on the regression equation, so remove any outliers if they are known to be errors
b: visual examination of the scatterplot shows that the poitns approximate a straight line pattern
c: the method for regression analysis line is not robut. its seriously affected by a small departrue from a normal dsitribution
d: the sample of paired (x,y) data is a random sample of quantitative data