Contrast (statistics)
In statistics, particularly in the analysis of variance and linear regression, a contrast is a linear combination of variables (parameters or statistics) whose coefficients add up to zero, allowing comparison of different treatments. == Definitions == Let θ 1 , … , θ t {\displaystyle \theta _{1},\ldots ,\theta _{t}} be a set of variables, either parameters or statistics, and a 1 , … , a t {\displaystyle a_{1},\ldots ,a_{t}} be known constants.