fd22

2^2 Factorial Design Analysis.

This m-file is used in experiments involving several factors where it is necessary to investigate the joint effects (main and interactions) of the factors on a response variable and determine by a formal analysis of variance which factor effects are nonzero. An important special case is that where each of the two factors (k = 2) of interest has only two levels. Because each of the replicate of such an experimental design has exactly 2^2 (=4) experimental trials or runs. So, this results the simplest design in the 2^k series. It is a basic block used to create other more complicated experimental designs.

Inputs:
D - matrix data (=[X Y]) (last column must be the Y-dependent variable). (X-independent variable entry for the 2^2 factorial design).
alpha - significance-value (default = 0.05).

Outputs:
A complete analysis of variance is summarized on a table.
[NOTE: If none of the variables on the model has a significant effect, should appers this note and does not proceed with the analysis of variance.]