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RE: st: RE: gpscore for propensity score of 4 observed groups
From
"Villa Lora, Juan Miguel" <[email protected]>
To
"[email protected]" <[email protected]>
Subject
RE: st: RE: gpscore for propensity score of 4 observed groups
Date
Tue, 12 Oct 2010 18:01:33 -0400
Stephen,
I haven't dealt with such case. Anyway, it seems to me that you don't have a control or comparison group without treatment. This situation may confound your evaluation and your results will be invalid.
Juan
________________________________________
From: [email protected] [[email protected]] On Behalf Of [email protected] [[email protected]]
Sent: Tuesday, October 12, 2010 5:32 PM
To: [email protected]
Subject: Re: st: RE: gpscore for propensity score of 4 observed groups
Hi Juan,
Yes, this is true, the treatment variable is categorical. I was worried that this would be an issue. That said, what command what provide a propensity score for a categorical variable with four levels?
Stephen
On Tue, 12 Oct 2010, Villa Lora, Juan Miguel wrote:
> Hey Stephen!
> Before answering your question I'd like to understand your treatment variable. You are stressing that you got four different groups, which makes me think that you are dealing with a categorical variable instead of a continuous variable as it's required for gpscore. Remember that Hirano and Imbens (2005) spell out that this treatment variable must be a normal distributed (one of the basic assumptions of the analysis). Are you sure your treatment variable is continuous?
> Juan
> ________________________________________
> From: [email protected] [[email protected]] On Behalf Of [email protected] [[email protected]]
> Sent: Tuesday, October 12, 2010 5:15 PM
> To: [email protected]
> Subject: st: gpscore for propensity score of 4 observed groups
>
> Hi,
>
> I have technical question regarding gpscore.
>
> If my treatment variable is type of injury severity, what should I put for "cutpoints", "index", and "nq_gps"? The treatment level has four different levels of injury severity.
>
> What I am seeking is to create a propensity score for the likelihood that a person develops a certain type of injury, in this case TBI, based upon a list of covariates.
>
> This is the syntax I used for a preliminary analysis:
>
> gpscore age child_gender prev_anxiety prev_depn prev_adhd prev_behavioral prev_other_mh, t(inj_severity) gpscore(mygps) predict(hat_inj_sev) sigma(hat_sd) cutpoints (inj_severity) index(p50) nq_gps(4)
>
> Again, I am unsure of cutpoints, index, and nq_qps given that I have four established groups for the treatment variable.
>
>
> Thank you,
> Stephen
>
>
>
>
> Stephen O'Connor
> Senior Fellow
> Harborview Injury Prevention & Research Center
> Department of Psychiatry & Behavioral Sciences
> University of Washington at Harborview Medical Center
>
>
>
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