Random Variance

Random Variance

A change in a statistical sample due to chance and not to a change in the underlying data. For example, 47% of one sample may prefer product A to product B, while only 42% do in a second sample. If the change is due to random variance, it does not indicate a decline in support for product A. Various models exist to account for random variance, notably large sample sizes and multiple surveys. See also: Outlier.