Question

a researcher is conducting an experiment to determine how different amounts of daily physical exercise (in minutes) affect systolic blood pressure in adults. the participants are assigned to different exercise groups

1. no exercise,
2. moderate exercise
3. intense exercise

then their systolic blood pressure is measured after 4 weeks. which of the following correctly identifies the independent and dependent variables in this experiment?
independent variable: no exercise, dependent variable: systolic blood pressure
independent variable: systolic blood pressure, dependent variable: amount of daily exercise
independent variable: amount of daily exercise, dependent variable: amount of daily exercise
independent variable: amount of daily exercise, dependent variable: exercise intensity
independent variable: systolic blood pressure, dependent variable: exercise intensity
independent variable: systolic blood pressure, dependent variable: systolic blood pressure
independent variable: amount of daily exercise, dependent variable: systolic blood pressure

Explanation:

In an experiment, the independent variable is what is manipulated (here, the amount of daily exercise with different groups: no, moderate, intense). The dependent variable is what is measured as a result (systolic blood pressure). The first option wrongly takes "no exercise" (a category of the independent variable) as the independent variable. The second option reverses the variables. The third option has the dependent variable wrong (shouldn't be amount of daily exercise again). The fourth option has wrong dependent variable (exercise intensity is part of how the independent variable - amount of daily exercise - is categorized). The fifth option has wrong independent variable. The correct relationship is independent variable (amount of daily exercise) affecting dependent variable (systolic blood pressure).

Answer:

Independent variable: amount of daily exercise, Dependent variable: systolic blood pressure