A researcher is interested in the effect of caffeine on a driver's braking speed.She takes four groups of participants and gives each group a different dose of caffeine,then measures their reaction time.Which of the following statements is true?
A) The dependent variable has four levels.
B) The independent variable has four levels.
C) The independent variable is reaction time.
D) The dependent variable is the number of groups.

Question

Quizplus · Accepted Answer

The independent variable is the dose of caffeine given to each group, which has four levels (four different doses). The dependent variable is the driver's braking speed, which is measured through their reaction time. Therefore, statement A is incorrect as the dependent variable is not the number of levels, and statements C and D are incorrect as they incorrectly identify the independent and dependent variables.

A Researcher Is Interested in the Effect of Caffeine on a Driver's