Exercise

Intercepts

In the previous exercise, you saw how to code multiple slopes. During this exercise, you will get to explore intercepts with model.matrix() using a simple vectors of colors. First, build a matrix including a reference intercept. This input only has the intercept variable's name (e.g. ~x1). Second, build a matrix including an intercept for each color. This input has the intercept variable's name and -1 (e.g. ~x1 - 1).

Instructions 1/2

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1
- Build a matrix using color including a reference intercept, which is the default option for R.
2
- Build a matrix using color including an intercept for each color, which requires a - 1 in the input.