-Zero conditional mean: There is no direct method to test for this assumption, so we just impose it on our
model. We assume that the expected value of the error term given any
values of the independent variable is 0.
-Homoskedasticity: There is also no direct method to test for this assumption, so we impose it on our data.
Thus, we assume that the variance of the error term due to any values of the independent variables is zero.