Other Incomplete Designs

If Factor B is nested in Factor A, it is impossible to separate the B main effect from the AB interaction. When effects cannot be separated, they are confounded. Whenever the factors in a design are not completely crossed, some effects will be confounded. However, in some designs the factors are neither completely crossed nor completed nested. The 4 × 6 design in Table 9.1 is an example; in this design, the factors are not completely crossed, yet neither is nested within the other. The analysis of most such partially nested designs is very difficult, but for certain designs it is relatively simple.