EXAMPLE 1 Predictor variables and response variables

For the following pairs of variables, identify which is the predictor variable and which is the response variable:

  1. The cost of an engagement ring, and the size of the diamond (in carats)
  2. The heights of primary school children, and their ages

Solution

  1. The cost of an engagement ring depends in part on the size of the diamond. We can use the size of the diamond to predict the cost of the ring. Thus, the diamond size is the predictor variable, and the cost is the response variable.
  2. Because the response variable depends on the predictor variable, and because a child's age depends on nothing but the calendar, then age cannot be the response variable. Age must therefore be the predictor variable, with height as the response variable.

NOW YOU CAN DO

Exercises 9–12.