Date: Fri, 7 Mar 2008 10:17:30 -0600
Reply-To: "Reutter, Alex" <areutter@spss.com>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: "Reutter, Alex" <areutter@spss.com>
Subject: Re: GEE: Binary logistic with repeated measures
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Hmmm. Let me make sure I understand your data setup. You have variables like:
Hunter Trip Encounter Pursuit
1 1 1 No
1 1 2 Yes
1 1 3 No
1 2 1 No
1 2 2 No
1 3 1 No
1 3 2 No
1 3 3 No
1 3 4 Yes
2 1 1 No
....
And so on, where Hunter ranges from 1 to the number of hunters; within Hunters, Trip ranges from 1 to the number of times each Hunter was followed; within Trips, Encounter ranges from 1 to the number animals encountered on each Trip. Pursuit marks whether or not the animal was pursued. You may have other factors and covariates that further describe the Hunter, Trip, or Encounter.
Does your REPEATED subcommand then look something like:
/REPEATED SUBJECT=Hunter WITHINSUBJECT=Trip*Encounter
?
If so, and you're getting the warning, then there is a duplicate combination of Hunter*Trip*Encounter that needs to be corrected.
If not, then what is your actual data setup and REPEATED subcommand?
Also, if I've understood correctly, even once you have this running properly GENLIN will be estimating a 45x45 working correlation matrix, which will likely cause its own problems. But get this to run before worrying about that.
Alex
-----Original Message-----
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of alleng
Sent: Thursday, March 06, 2008 2:54 PM
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: Re: GEE: Binary logistic with repeated measures
Thanks Alex, that was helpful. Unfortunately, the program still won't let me
analyze the data set because it is telling me that there are at least two
records with the same values for the subject and within-subject variables.
I'm not sure if this is a data error on my part or due to the structure of
my data. In the wheeze example each subject has four measures, however, in
my data the number of encounters (cases) is highly variable so that one
individual may be represented 12 times and another may be represented 45
times depending not only on how many times they were followed in the field
but also how many times they actually were successful in encountering an
animal. Could this be the reason that it is not permitting the analysis?
Cheers,
Allen
Reutter, Alex wrote:
>
> Have a look at the wheeze_steubenville.sav dataset that ships with SPSS
> and the associated Case Study (Help > Case Studies... and navigate to the
> GEE section, or click on the "Show Me" link in the main GEE help topic).
> That should show you the data structure for a repeated measures binary
> logistic.
>
> Alex
>
>
> -----Original Message-----
> From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
> alleng
> Sent: Wednesday, March 05, 2008 7:41 PM
> To: SPSSX-L@LISTSERV.UGA.EDU
> Subject: GEE: Binary logistic with repeated measures
>
> I'm trying to run a GEE analysis in SPSS 16 and not getting very far at
> this
> point as this is new territory for me. I am trying to analyze the
> probability of pursuit upon encounter for individual hunters in the Amazon
> of Bolivia. The repeated measure is the ID of each hunter. Each hunter
> was
> followed anywhere from one to five times while in the forest (trip id is
> repeated to every time there is a new encounter). On each of his follows
> he
> may or may not have encountered any number of animals which he then must
> decide whether or not to pursue. As it stands now I am trying to use the
> ID
> as the subject variable but keep getting the error message:
>
> Warnings
> There are at least two records with the same values for the subject and
> within-subject variables. No output will be displayed.
> This command is not executed.
>
> How does my data need to be structured in order to run this type of
> analysis
> given the nature of my data?
>
> Any insight would be greatly appreciated.
>
> Cheers,
> Allen Gillespie
> University of Auckland
>
> --
> View this message in context:
> http://www.nabble.com/GEE%3A-Binary-logistic-with-repeated-measures-tp15864680p15864680.html
> Sent from the SPSSX Discussion mailing list archive at Nabble.com.
>
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