Question

Suppose you want to study the relationship between smoking and cancer. You assume that smoking is a cause of cancer. Studies have shown that there are many factors affecting this relationship, such as the number of cigarettes or the amount of tobacco smoked every day; the duration of smoking; the age of the smoker; dietary habits; and the amount of exercise undertaken by the individual. All of these factors may affect the extent to which smoking might cause cancer. These variables may either increase or decrease the magnitude of the relationship. Which statement is false?

a. In the above example cancer is the dependent variable.
b. In the above example cancer is an independent variable.
c. In the above example the extent of smoking is an independent variable.
d. In the above example all the variables that might affect the relationship between smoking and cancer, either positively or negatively, are extraneous or mediating/moderating variables.

Answer 1

The correct answer is:

In the above example cancer is an independent variable. (b)

Explanation:

In order to explain the choice made, let m first explain what independent and dependent variables are:

Independent variable: An independent variable is a variable that is under the direct control of the experimenter, and can be changed at will. In this example, the number of cigarettes or amount of tobacco smoked is the independent variable because it can be manipulated at will, to determine the outcome of the dependent variable.

Dependent variable: A dependent variable is a variable that the experimenter sets out to study. The independent variable is not under the direct manipulation of the experimenter but has values that come about as a result of the change of the independent variable. In this example, cancer is the dependent variable, because it is the result of the manipulation of the amount of tobacco.

Therefore, it is not true to say that cancer is the independent variable as seen in option b