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Antwort: st: RE: RE: graph for propensity scores
That?s exactly the reason why propensity scores should be shown in the
?upwards and downwards? design, since the graph shall show that both
groups do have a common support area.
I?ll check the reference anyway.
Hans J. Baumgartner
Dept. Public Economics
German Institut for Economic Research
fax : +49/30/89789-114
email@example.com wrote on 12/04/2005 15:57:22:
> Upwards and downwards designs appear popular
> for no good reason. In effect the reader is
> expected to be able to pick up one length,
> transfer it and superimpose it, all in one's
> head, upon another length. Why this should be easier
> or more effective than comparing juxtaposed lengths
> beats me.
> The same issue arises with left and right
> (side-by-side) designs such as population
> In each case, small and subtle differences
> could easily be of interest or importance.
> The problem with histograms is naturally the
> loss of detail produced by binning. Often
> this is unimportant but frequently a researcher
> does want to be sure that is so.
> To compare two sets of values qua distributions,
> -qqplot- is pretty nearly an optimal plot. To
> compare them as paired values, there are several
> good methods. A fairly lengthy discussion with
> references is given in
> Graphing agreement and disagreement.
> Stata Journal 4(3): 329--349 (2004)
> David Harrison
> > You could do that something like, e.g.
> > sysuse auto
> > twoway__histogram_gen length if !foreign, start(140) w(10)
> > freq gen(h0 x0)
> > twoway__histogram_gen length if foreign, start(140) w(10)
> > freq gen(h1 x1)
> > replace h1=-h1
> > gen zero=0
> > twoway (rbar h0 zero x0, barw(10)) (rbar h1 zero x1, barw(10)), ///
> > yla(-10 "10" -5 "5" 0(5)15) yti(Frequency) ///
> > legend(label(1 "Domestic") label(2 "Foreign"))
> > Note the very handy command -twoway__histogram_gen- (two
> > underscores in the first gap!) that is not in the Stata
> > manuals but does have a help file.
> Hans J. Baumgartner
> > I am estimating treatment effects using propensity scores.
> > To discuss the common support I?d like to graph the scores for the
> > treated and the controls.
> > However, my graph knowledge is very limited and is only sufficient to
> > generate a graph, where the scores for the treated and the
> > controls are
> > displayed next to each other. That is I am using the by(.) option and
> > the command historgram.
> > I?ve seen the scores are displayed upwards for the treated
> > and mirrored
> > downwards for the controls in one single graph.
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