input levels v/s contributions

From: josh milkwood (lordsimplex_at_yahoo.com)
Date: 01/17/05 

Date: 17 Jan 2005 03:46:42 -0800

Hi

I have been using L9 orthogonal array for a 4 factor, 3-level process
(with Design-Expert) and worked out contributions of each factor.
However the input signal for Factor A is in log scale whereas input
signals for B, C & D are doubled over each level (geometric). To make
things clear I reproducing my data here.

Factor Levels Level steps Contributions obtained
A 1, 10, 100 Log increment 40
B 5, 10, 20 Geometric 30
C 1, 24, 48 Geometric 20
D 24, 48 ,72 Geometric 10

My question is: Does the fact that factor A input is incremented on a
log scale distort factor contribution and/or skew my main effects plot.
Hope I am clear

Many Thanks, josh