The test statistics is:
- is the value of the th of observations in the th of groups, where has been 'centered' such that ,
- is the average in the th group,
- is the overall average,
- is the calibrated weight,
- , and
- is computed using the Greenhouse-Geisser method.
- and is evaulated using the F-distribution with and degrees of freedom, where .
- ↑ Huynh, H., & Feldt, L.S. (1976). Estimation of the Box correction for degrees of freedom from sample data in randomised block and split-plot designs. Journal of Educational Statistics, 1, 69-82.