Date:         Fri, 23 Sep 2005 07:07:48 -0400
Reply-To:     John Painter <painter@email.unc.edu>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         John Painter <painter@email.unc.edu>
Subject:      Re: Propensity score matching
Comments: To: Alice Sullivan <A.Sullivan@ioe.ac.uk>
In-Reply-To:  <DDEFF61292422A4A9B8EF93B3D11BBDD90A72E@bgmail01.ioead>
Content-Type: TEXT/PLAIN; charset=US-ASCII

Hello,

There is a SPSS program for propensity matching at my web site:
www.unc.edu\~painter


~ John Painter



On Fri, 23 Sep 2005, Alice Sullivan wrote:

> Hi,
>
>
>
> I am doing an analysis of academic outcomes for children in private and
> state schools, and am trying to use the propensity score approach.
>
>
>
> I want to match on the exact propensity score, dropping unmatched cases
> from the sample. I did try the binning approach, but since my dataset is
> large (more than 10,000 cases), it was impossible to balance the bins.
>
>
>
> I have calculated the propensity score using 'save predicted values -
> probabilities' in binary logistic regression, with the 'treatment'
> (state/private school) as the dependent variable, and a set of
> predictors (social class, etc), as follows:
>
>
>
> LOGISTIC REGRESSION  private
>
>   /METHOD = ENTER region3s faclas7m educatio famtrad kidno mobooks moint
> Zabilit11 teacha_1 teachmiss abilmiss
>
>   /CONTRAST (region3s)=Indicator  /CONTRAST (faclas7m)=Indicator
> /CONTRAST (educatio)=Indicator  /CONTRAST
>
>   (famtrad)=Indicator  /CONTRAST (kidno)=Indicator  /CONTRAST
> (mobooks)=Indicator  /CONTRAST (moint)=Indicator  /CONTRAST
>
>   (abilmiss)=Indicator  /CONTRAST (teachmiss)=Indicator
>
>   /SAVE = PRED
>
>   /CRITERIA = PIN(.05) POUT(.10) ITERATE(20) CUT(.5) .
>
>
>
> My problem is that the number of values I get from this is huge -  it
> exceeds 1000, so I can't even run a crosstabs. I can run a table of
> frequencies, but it's too huge to print out.
>
>
>
> My questions are:
>
> 1.      Am I doing something wrong?
> 2.      Is it acceptable to group the propensity scores together - e.g.
> into percentiles or deciles, before dropping unmatched cases, or would
> this defeat the object?
> 3.      Has anyone written syntax to identify/drop unmatched cases?
> (Doing it by hand is a daunting task with so many values!).
>
>
>
> Many Thanks,
>
> Alice
>
>
>
>
>
> Dr. Alice Sullivan
>
> Centre for Longitudinal Studies
>
> Institute of Education
>
> 20 Bedford Way
>
> LONDON
>
> WC1H OAL
>
>
>