Control Variable

What is Control Variable?

A variable deliberately held constant across every tube in an investigation so that it cannot affect the result. In food testing the control variables include sample mass or volume, sample preparation, reagent volume and concentration, heating temperature, heating time, mixing method and observation conditions. Holding them constant is what allows a difference in colour to be attributed to the food rather than to the method.

This definition is part of the Biological Molecules chapter in Cambridge O Level Biology.

Concepts related to Control Variable

• independent variable
• positive control
• cross-contamination