Mathematics and Applied Statistics Lesson of the Day – Contrasts
June 19, 2015 3 Comments
A contrast is a linear combination of a set of variables such that the sum of the coefficients is equal to zero. Notationally, consider a set of variables
Then the linear combination
is a contrast if
There is a reason for why I chose to use as the symbol for the variables in the above notation – in statistics, contrasts provide a very useful framework for comparing multiple population means in hypothesis testing. In a later Statistics Lesson of the Day, I will illustrate some examples of contrasts, especially in the context of experimental design.