A response variable measures an outcome of a study. It is the particular quantity about which questions are asked. An explanatory variable is any factor that can influence the response variable. An explanatory variable attempts to explain the observed outcomes. The response variable is usually called dependent, while the explanatory variable is sometimes called independent.
Whereas a study can be without a response variable, there can be several explanatory variables. The naming of a response variable is determined by the type of study. An observational study is an example of an investigation without a response variable, as when a researcher studies the mood and attitudes of a group of first-year students. All the first-year students may be given several questions to examine the homesickness degree of a student. Students may also indicate how distant home is from the college. A researcher examining this data may only be interested in the students’ responses, perhaps simply to have an overall perspective as regards the attitudinal makeup of a new freshman. In such a case, the response variable is missing because it cannot be seen how the value of one variable influences the value of another.
A second researcher may use the same data and try to answer if there is a greater degree of homesickness in students who came from further away. In this scenario, the data relating to homesickness questions constitute the values of a response variable. The distance from home, in this case, is the explanatory variable.