Date:         Thu, 19 Oct 2006 04:22:52 -0700
Reply-To:     Chrissy Wissy <cjsilwood@TISCALI.CO.UK>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Chrissy Wissy <cjsilwood@TISCALI.CO.UK>
Organization: http://groups.google.com
Subject:      Categorical variable codings
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset="iso-8859-1"

Hi,
I am trying various regression analyses on data obtained from the study
of 6 different cooking oils, control and 4 different material
treatments, all samples being sampled at 30 min, 60 min and 90 min
heating. I am wondering what a suitable set of categorical variable
codes to use for comparing, e.g. material/time or oil/material/time,
i.e. 5 X 3 or 6 X 5 X 3 at all levels and interactions, assuming with
the latter that "oil" can be included as an independent variable.

Thanks