I have the regression
$$ y = \beta_0 + \beta_1 x_1 + \beta_2 D + \beta_3 x_1 D + \varepsilon $$
where $x_1$ and $y$ are continuous, and $D$ is binary. Say the estimates are as follows:
$$ y = 0.02 + 0.5 x_1 + 2 D + 0.7 x_1 D + \varepsilon $$
- What is the interpretation of $\beta_3$?
- How do I get the 'total effect' of $x_1$ and $D$? Is it $\beta_1 + \beta_3$ or is it $\beta_1 + \beta_2 + \beta_3$?