A nutrition study measured how many helpings of vegetables each of 125 grade school children were served each week during a school year and their body mass index (BMI) scores. Which variable would one put on the horizontal axis of a scatterplot of the data?
A) One would put the BMI score because it is the response variable.
B) One would put the BMI score because it is the explanatory variable.
C) One would put helpings of vegetables because it is the response variable.
D) One would put helpings of vegetables because it is the explanatory variable.
E) It makes no difference because there is no explanatory-response distinction in this study.

Question

Quizplus · Accepted Answer

In this study, the number of helpings of vegetables is the explanatory variable because it is the variable that is being manipulated to see its effect on the BMI scores of the children. Therefore, it should be plotted on the horizontal (x) axis. The BMI scores are the response variable, which will be affected by the number of helpings of vegetables, and should be plotted on the vertical (y) axis.

A Nutrition Study Measured How Many Helpings of Vegetables Each