A variable, in research and data collection, refers to something that is being measured and can have changing values.
The example above shows that student birth month is a variable since we can have a range of options from January to December. Political affiliation is also a variable since the students can state whether they follow certain political parties or even whether they do not. Student age is a variable too, with answers from a range of numbers such as 20-25, since they are college students. Student address is a variable as well since students will have varying answers, be it those who live in the same address or different ones.
However, number of students in the data set is not a variable – it is instead the number of research participants. It can be a population or a sample, depending on what the research is about.
