[R] Normal probability plot examples for Wikipedia (was "qqnorm with histogram?")

Spencer Graves spencer.graves at structuremonitoring.com
Mon Aug 4 18:55:54 CEST 2014

Hi, Jim et al.:

       Thanks for the reply, Jim.

       What are your favorite examples using normal probability plots to 
identify outliers, skewness, kurtosis, mixtures, and the need for 
transformations in plots of raw data and residuals from model fits -- or 
using half-normal plots with estimated parameters?

       I ask, because I believe the current Wikipedia article on "Normal 
probability plot" could be improved dramatically with a set of great 
examples.  I also plan to write a function to display a normal 
probability plot with a histogram, a density estimate, and a boxplot and 
use it with the examples.  My current plan is to create this with a 
function qqnormPlus(..., datax=TRUE, histargs, densityargs, boxplotargs) 
that passes histargs, densityargs and boxplotargs to truehist{MASS}, 
density, and boxplot, respectively.  I plan to add this to the Ecfun 
package (for which I'm the author and maintainer).

       This wikipedia article received 14774 views in the past 90 days, 
averaging not quite 700 per day, so I think it's worth doing.  I could 
use suggestions (and help from other Wikipedians on this list).


On 8/3/2014 2:59 PM, Jim Lemon wrote:
> Hi Spencer,
> The last example for the twoord.plot function (plotrix) does this.
> Jim
> On Sun, 3 Aug 2014 12:38:10 PM Spencer Graves wrote:
>>         Does a function exist that combines a normal probability plot
>> with a histogram and maybe a density estimate on the same plot?
>>         I'm revising the Wikipedia article on "Normal probability plot",
>> and I think it would be good to provide examples of this.
>>         Thanks,
>>         Spencer
>> p.s.  Please reply also with suggestions for how to improve that
>> Wikipedia article if you feel so inclined.
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