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 fory ~ 1 + x
(where1 +
is the intercept in the model), and thus you can omit1 +
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.
This exercise is part of the course
Hierarchical and Mixed Effects Models in R
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Use a linear model to estimate how math kindergarten
# scores predict math gains later
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