1. The partial slope corresponds to the direct effect in a path diagram.
2. The indirect effect of an explanatory variable is the difference between the marginal and partial slopes.
3. If we reject H0: β1 = β2 = 0 using the F-test, then we should conclude that both slopes are different from zero.
4. If we reject H0: β2 = 0, then we can conclude that the increase in R2 obtained by adding X2 to the regression is statistically significant.
5. The main use for a residual plot is finding nonlinear effects in multiple regression.
6. A calibration plot summarizes the overall fit of a regression model.