to vary / a variable

When something varies, it means it's not always the same. So, for example, the number of students attending lectures varies from day to day. A variable is something that can change. It’s common to research variables to show how changing one thing can change something else. Let’s say, for instance, your research question is whether people in New Zealand watch the TV news more as they get older. (This information could be useful for companies who want to target older age groups!). Here, age is your independent variable and the number of hours people watch TV news is your dependent variable. So, basically, you’re researching whether a change in the age (the independent variable) affects the hours of TV news watched (the dependent variable). In quantitative research, variables have to be controlled so that researchers can be sure that the results they see really are connected together and not related to something else (if someone watches more TV news than someone else it might be connected with their age, but it could be more to do with their education level, economic status, personality etc etc). The problem in research is when there are too many variables!

Demand for energy varies considerably according to the weather, the time of day.

The subjects were grouped according to their economic circumstances, but other variables such as educational level, gender and ethnicity were ignored.

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