that factor A is at the high level and factor B is at the low level. The run with both factors at
the low level is represented by (l). This notation is used throughout the family of 2k designs
For example, the run in a 24 with A and C at the high level and B and D at the low level is denoted by ac.
The effects of interest in the 2k design are the main effects A and B and the two-factor
interaction AB. Let the letters (1), a, b, and ab also represent the totals of all n observations
taken at these design points. It is easy to estimate the effects of these factors. To estimate the
main effect of A, we would average the observations on the right side of the sqtiziw: wlien A is
at the high level and subtract from this the average of the observations on the left side of the
square where A is at the low level, or