StATS: What is an independent variable?
A variable that you believe might influence your outcome measure. This might be a variable that you control, like a treatment, or a variable not under your control, like an exposure. It also might represent a demographic factor like age or gender. Contrast this with the definition of the dependent variable. An independent variable is a hypothesized cause or influence on a dependent variable. One way to distinguish these variables is to ask yourself what you are want to learn from this research. The dependent variable is a variable you are trying to predict. Any variable that you are using to make those predictions is an independent variable. A recently published research study examined the relationship of dietary fat consumption and the development of ischemic stroke in a cohort of 832 men who were free of cardiovascular disease at baseline (1966-1969) and who were followed for a twenty year period. In this study, the independent variables were:
This page was written by Steve Simon while working at Children's Mercy Hospital. Although I do not hold the copyright for this material, I am reproducing it here as a service, as it is no longer available on the Children's Mercy Hospital website. Need more information? I have a page with general help resources. You can also browse for pages similar to this one at Category: Definitions, Category: Hypothesis testing.