Date:         Mon, 27 Oct 2008 01:13:02 -0700
Reply-To:     "cat.." <cat.b41@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "cat.." <cat.b41@GMAIL.COM>
Organization: http://groups.google.com
Subject:      To statisticians: Units, standardization and regression modelling
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset=ISO-8859-1

Hi there,

Let's say I want to fit a logistic model Logit P(diabetis) = Age +
Glucose.

I usually do not ask for standardizing the covariates before entering
them into the model, only centering them, just to make the
interpretation of exp(beta) easier (= OR when the covariate is
incremented by 1 <unit used in the model>). Centering the covariate
impacts the value of the intercept, reducing them will impact the
value of their coefficient in the model.

But now, I have a doubt: What about the units ? What senses does it
make to add years and mg/dl ?

Any thought about that ?

What is your practice in modeling ? Do you always only work with
standardized variables ?

Thanks to any contributor.

Catherine.