Date:         Fri, 12 Jan 2007 16:28:10 -0500
Reply-To:     Kevin Roland Viel <kviel@EMORY.EDU>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Kevin Roland Viel <kviel@EMORY.EDU>
Subject:      Re: normality of residuals: opinions?
In-Reply-To:  <1168636745.960459.59010@l53g2000cwa.googlegroups.com>
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Fri, 12 Jan 2007, Reeza wrote:

> Looks like your residuals do not pass the tests for normality, and
> assuming your errors are in some order relative to the data collection
> or observation there also appears to be some evidence of cyclical
> patterns.  time series data?

Thanks.  The data are a plasma protein level measured once.  There should
be no period effect.  As for the normality tests, they may be sensitive to
outliers, among other problems:

data resid ;
  do _n_ = 1 to 100 ;
    e = rannor( 0 ) ;
    output ;
  end ;
  e = 10 ;
  output ;
run ;

proc univariate data = resid ( obs = 100 ) normal ;
  var e ;
run ;

proc univariate data = resid normal ;
  var e ;
run ;


Kevin Viel
PhD Candidate
Department of Epidemiology
Rollins School of Public Health
Emory University
Atlanta, GA 30322