Question

A researcher was interested in the impact of exercise on tumor growth in mice. She took 50 mice with tumors and measured the size of their tumors. She then had them walk each day on the treadmill for 6 weeks. All of the mice were fed the same diet, held under the same environmental conditions and required to walk the same amount on the treadmill. At the end of the experiment, she measured the size of their tumors and calculated the change in size. What is the independent variable in this experiment? the dependent variable? the control ?

Answer 1

An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable. A dependent variable is the variable being tested and measured in a scientific experiment.Here, effects of exercise is tested on tumor growth by measuring the size of tumor, after a week of exercise.Therefore exercise is the independent variable and tumor size is the dependent variable. A control variable is an element that is not changed throughout an experiment, which in this case includes diet, environmental conditions and amount of exercise.Control group (not mentioned in the experiment) would be a group of mice whose tumor sizes are measured without performing the exercise.