Slopes and multiple regression

Previously, you used multiple intercepts to model the expected values for discrete groups. Now, you will model continuous predictor variables with slopes.

In particular, you will model gains in math test scores by building three different models.

The data, school_3_data, has been loaded for you.

Notes:

• y ~ x is a shortcut for y ~ 1 + x (where 1 + is the intercept in the model), and thus you can omit 1 + in your formulas.
• Multiple regression use a + in the formula (e.g., y ~ x_one + x_two).
• Use the interaction shortcut syntax y ~ x_one * x_two so the testing software will correctly score your answer.