[R] Looking for the name of a certain kind of quantile plot

[cberry at tajo.ucsd.edu]

Carl Witthoft <carl at witthoft.com> writes:

> Hi,
> While playing with quantile-quantile plots, I wrote up some code which
> plots something strangely different.  Here's the pseudocode:
>
> testhist <- hist(sample_data)
> refhist <- hist(rnorm(n, mean=0,sd=1))  # for some large-ish n
> cumtest <- cumsum(testhist)
> cumref <- cumsum(refhist)
>
> plot(cumref,cumtest)


Sounds like a 'pp-plot'. See

      http://en.wikipedia.org/wiki/P-P_plot

Why not provide reproducible code?

Chuck

>
> This produces a straight line of slope 1 for a sample with the same
> parameters as the reference sample, and produces S-curves for samples
> with different sigmas.  A sample with nonzero mean looks almost
> exponential (or logarithmic, depending on the sign of the mean).
>
> So my question is: is there a name for this sort of plot,  and is it
> of any real use in statistical analysis?
>
> thanks.
> Carl

-- 
Charles C. Berry                            Dept of Family/Preventive Medicine
cberry at ucsd edu			    UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901