what does it mean to hold variables constant
Controlling for a variable In controlled experiments, researchers randomly assign individuals to a treatment group or control group. This is done to reduce the confounding effect of irrelevant variables that are not being studied. In an observational study, however, researchers have no control over who receives the treatment. Instead, they must control for variables using statistics. Controlling for a variable holds that variable constant for calculations made about the effect of the independent variable on the dependent variable.