Date:  Mon, 26 Apr 1999 15:00:04 0300 
ReplyTo:  hmaletta@overnet.com.ar 
Sender:  "SPSSX(r) Discussion" <SPSSXL@UGA.CC.UGA.EDU> 
From:  "Hector E. Maletta" <hmaletta@OVERNET.COM.AR> 
Subject:  Re: is variable aspect a constant? 

ContentType:  text/plain; charset=usascii 
Dana,
if I read well your message, your new variable resefc1 will have a valid
value only when recefc2 fails to be given a valid value, and vice versa.
Then, there would be no case with a pair of valid values in recefc1 and
recefc2, and no correlation could be computed between them!! (except
you thoughtfully gave, say, a zero value to recefc1 when assess=2 and a
zero value to recefc2 when assess=1).
On the other hand, it is logically possible, though seemingly unlikely,
that all cases with assess=1 have the same value on recefc (or all cases
with assess 2 have the same value on recefc), and this would generate
the message you receive.
Hector Maletta
Universidad del Salvador
Buenos Aires, Argentina
> Dana Ross wrote:
>
> Hello!
>
> I have a question about defining variables that are used in
> testretest correlations.
>
> If I have a variable that is computed under the If statement, does
> that "If" condition make the new variable a constant? for instance,
> i have a computed variable "resefc" that is computed as the sum of
> responses 6365. I have computed two other variables "resefc1"
> (which is resefc IF assess=1) and "resefc2" (which is resefc IF
> assess=2).
>
> in this case, does the "assess" variable act as a constant? I ask
> because I am unable to do bivariate correlations on resefc1 and
> resefc2; i keep getting a message that indicates "one or more of the
> variables is a constant".
>
> any help would be appreciated.
>
> Dana Ross
> grad student
> University of Alabama at Birmingham
>
>
