Solomon wants to verify that automatic toothbrushes work better than manual toothbrushes. To test this, he randomly assigns 25 participants to use a Sonicare toothbrush and 25 people to use a manual toothbrush. At the end of the study period he has a dentist inspect each participant's teeth. In this study, the _____ would be considered the independent variable, whereas the _____ would be considered the dependent variable.
A) type of toothbrush; number of cavities
B) manual toothbrush; automatic toothbrush
C) automatic toothbrush; manual toothbrush
D) number of cavities; type of toothbrush

Question

Quizplus · Accepted Answer

The independent variable is the one that is changed or controlled in a scientific experiment to test the effects on the dependent variable. In this case, the type of toothbrush (automatic vs. manual) is the independent variable because it is what Solomon is manipulating. The dependent variable is the outcome that is being measured, which is the number of cavities, as it depends on the type of toothbrush used.

Solomon Wants to Verify That Automatic Toothbrushes Work Better Than