I have a basic question.
If I have a 2^2 factorial design like this (4 runs)
X1 X2
-1 -1
-1 1
1 -1
1 1
the column vectors are orthogonal, but just what are they vectors of? What are the basis vectors? I'm trying to draw this on a graph (OK, really hard with four dimensions, but even trying two dimensions for a one-factor experiment). Or is there a much more general concept of "vector" going on here?
