A psychologist wants to know if eating a large breakfast improves IQ test scores in a sample of thirty 10-year-olds.The psychologist divides the subjects into three groups of ten and has one group eat a small breakfast,one group eat a medium-sized breakfast,and one group eat a large breakfast.In this study,the independent variable is:
A) the IQ test
B) the scores on the IQ test
C) the size of the breakfast
D) the number of subjects in each group

Question

Quizplus · Accepted Answer

The independent variable is the one that is manipulated in the study and in this case, it is the size of the breakfast. The psychologist is deliberately varying the size of the breakfast to see if it has an effect on IQ test scores. The IQ test and the scores on the IQ test are not being manipulated and are therefore not independent variables. The number of subjects in each group is also not being manipulated and is therefore not the independent variable.

A Psychologist Wants to Know If Eating a Large Breakfast