6P.6—Variables and controls

The independent variable is changed deliberately; the dependent variable is measured; controlled variables are kept constant so any difference can be attributed to the independent variable.

In a temperature–enzyme investigation, temperature is independent, oxygen volume per minute is dependent, and substrate concentration, pH and enzyme volume are controls.

A control group or baseline provides comparison, while a range and repeats reveal whether a relationship is consistent.

A variable can be measured accurately yet still be a confounder if it changes with the treatment.