Variance

Variance is a statistical measure that shows how much a set of values differs from the average. Understanding variance helps marketers identify patterns, evaluate risks, and know whether test outcomes are reliable or due to random chance. It’s central in interpreting A/B test results accurately.

In experimentation, variance helps determine if differences between control and test groups are meaningful. For instance, if two landing pages show different conversion rates, variance tells us whether that difference is consistent or just noise.

Businesses must account for variance to avoid false positives and wrong decisions. Without this, teams may implement changes that don’t truly impact performance long-term.