Question

Sickle-cell disease is a painful disorder of the red blood cells that in the United States affects mostly African-Americans. To investigate whether the drug hydroxyurea can reduce the pain associated with sickle-cell disease, a study by the National Institutes of Health gave the drug to 150 sickle-cell sufferers and a placebo to another 150. The researchers then counted the number of episodes of pain reported by each subject. What is the response variable in this study

Answer 1

The response variable is the episodes of pain reported

Explanation:

A response variable, also known as the dependent variable or explanatory variable, is the variable that is not under the direct control of the researcher, but whose value varies with the changing of the independent variable. The response variable is the focus of the experimental question.

In this example, the effect of the drug hydroxyurea is to be tested on sickle-cell patients, hence the drug used is the independent variable, because the experimenter can choose to give the subjects either hydroxyurea or a placebo, hence it is under the direct control of the experimenter. However, the result ( differences in episodes of pain) is a response to the administered drug or placebo.