Re: propensity score for 3 treatments

Posted by la volta statistics on Nov 30, 2012; 3:34pm
URL: http://spssx-discussion.165.s1.nabble.com/propensity-score-for-3-treatments-tp5716540p5716548.html

Thanks Matthew,  Eugene, and Bruce

I thought of NOMREG as well but then you get a probability for each
category. So how would that be used as a score?
Christian



On Fri, 30 Nov 2012 10:11:28 -0500
  "Maguin, Eugene" <[hidden email]> wrote:

> I first thought of an ordinal regression but then realized that
>there is no assurance that the parallel lines assumption would be met
>and then switched to multinomial regression. Maybe this is not a
>problem but the usual propensity setup has matching on the computed
>logit or log odds value from a logistic regression with a dichotomous
>DV. But with a three category DV you get two computed logits or log
>odds values irrespective of whether you use ordinal or multinomial.
>So how is the matching to be done.
>
> You've got to figure that this problem has come up before and an
>accepted method has been developed; however, I don't know what it is.
>My suggestion is to average the logits and match on that (but check
>the resulting match to see how well the match is on each logit
>value). My rationale is that if you formed matched triplets and
>assigned them to condition then did the multinomial regression
>analysis, each member of the triplet would have the same average
>logit and logit components.
>
> Gene Maguin
>
> -----Original Message-----
>From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf
>Of Bruce Weaver
> Sent: Friday, November 30, 2012 9:39 AM
> To: [hidden email]
> Subject: Re: propensity score for 3 treatments
>
> Multinomial logistic regression (NOMREG)?
>
>
>
> la volta statistics wrote
>> Hi all
>>
>> To control for confounding bias from non-random treatment assignment
>> with
>> 3
>> different treatments, I would like to calculate a propensity score I
>> later can use in a cox regression model. I know the procedures for a
>> two-treatment approach (logistic regression). But how would I
>> calculate such a score when I have three treatments?
>>
>>
>>
>> Thanks in advance
>>
>> Christian
>>
>>
>>
>>
>>
>> **********************************
>> la volta statistics
>> Christian Schmidhauser, Dr.phil.II
>> Weinbergstrasse 108
>> CH-8006 Zürich
>> Tel: [phone]
>> Fax: [phone]
>> email:  &lt;mailto:
>
>> schmidhauser@
>
>> &gt; mailto:
>
>> schmidhauser@
>
>>
>> Web:  &lt;http://www.lavolta.ch&gt; www.lavolta.ch
>
>
>
>
>
> -----
> --
> Bruce Weaver
> [hidden email]
> http://sites.google.com/a/lakeheadu.ca/bweaver/
>
> "When all else fails, RTFM."
>
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> To send me an e-mail, please use the address shown above.
>
> --
> View this message in context:
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