Splitting a continuous variable into two groups at its median is sometimes used in data analysis. On average, splitting a predictor variable

is equivalent in correlation and regression to replacing all the

values with either the mean

value for the low group or the high group, as appropriate. Each data value

is replaced by the weighted average

, where

is the mean for the group containing

and

is a weight value with

. Moving the weight slider to the right moves the

values toward a median split. Observe the decrease in

, the

-statistic, its

-value, and the predictor's variance as the data is moved towards the equivalent of a median split. Much is lost and nothing gained by a median split.