Conditions For Regression Slope Inference

Question

Which one of the following is NOT a necessary condition for the validity of inference on the regression slope?

Accepted Answer

The predictor variable (x) must be normally distributed.

Answer

The scatterplot of the data should reveal a linear trend.

Answer

The standard deviation of the response variable (y) should remain roughly constant across values of x.

Answer

The errors in the response variable (y) for each level of x should be approximately normally distributed.