Re: st: overlapping histograms

[Jeph Herrin <junk@spandrel.net>]

This audience knows about normal curves, and histograms,
and tails. That's about all they know, so I think the
graph I want is the right one. Anyway, it's not my
presentation.

I was deliberately ambiguous about "the nation" in the
interests of data privacy. If you want to guess I meant
the USA, then I suppose that reflects your bias, not
mine.... :)

P.S. I mentioned stripes to amuse, not to proselytize,
as we've been over that ground often enough before.


Nick Cox wrote:
> Audience is crucial -- no disagreement there.
>
> But your very clear implication is that you want to look at shifts in 
> distribution and see how far they are consistent across the range: an 
> excellent substantive question.
>
> I know no more direct way to do that than to look at quantile functions, 
> or equivalently their inverses. Histograms just obscure the details 
> through arbitrary decisions on bin width and origin.
>
> References to "the nation" are ambiguous on an international list. I 
> guess in your case you are discussing the USA.
>
> P.S. No votes from me for stripes, polka dots or other such graphjunk.
>
> Jeph Herrin wrote:
>
> > Nick Cox wrote:
> >  > It is good to know that you can do this. My guess is that many users
> >  > would like to see it written up somewhere.
> >  >
> >  > However, these histograms tend to lead only to crude inferences. Users
> >  > can't read off quantitative conclusions from the graph, just stuff
> >  > like "The distributions are about the same", or "... very different",
> >  > etc.
> >
> >
> > It all depends on the audience, doesn't it? This is for a
> > presentation about quality improvement in health care for
> > a certain treatment. The mantra for many years has been
> > that you don't want to fix just the poor performers - you
> > want to "shift the curve". It's the right mantra, because
> > every patient benefits (here, from faster treatment times);
> > and for the mantra, this is the right figure to show people
> > responsible for improving patient care. In three years, the
> > national curve shifted noticeably.
> >
> > Not exactly on list topic, but the point is that Stata is
> > only improved by letting users do what they want in graphics
> > (striped bars comes to mind...).
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