[R] R Commander QQ Plot with triangular distribution

[John Fox]

Dear R. Males,

This isn't really an R Commander question, since the qqPlot() function is in
the car package and is just invoked by the R Commander.

>From ?qqPlot: "distribution: root name of comparison distribution - e.g.,
"norm" for the normal distribution ... Any distribution for which quantile
and density functions exist in R (with prefixes q and d, respectively) may
be used." Thus, if there's a qtriangle() and dtriangle(), I suppose that you
should be able to get a QQ plot. Further from ?qqPlot: " ... 	arguments
such as df to be passed to the appropriate quantile function." Thus, you
should *name* the arguments to be passed to qtriangle() -- perhaps (of
course, you should use the correct names) min=3000, max=5000, mode=4000.

I hope this helps,
 John

--------------------------------
John Fox
Senator William McMaster
  Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox




> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
> On Behalf Of Richard and Barbara Males
> Sent: March-08-11 10:49 AM
> To: r-help at r-project.org
> Subject: [R] R Commander QQ Plot with triangular distribution
> 
> I am attempting to use the R Commander Graphs Quantile-Comparison
> functionality on a dataset, to compare with a triangular distribution.
>   I have the package triangle.   My question is on the syntax of how
> to specify the parameters of the theoretical distribution in the
> Parameters field of the dialog box.  For example, the theoretical
> distribution has min of 3000, max of 5000, mode of 4000.   When I
> enter this info as 3000,5000,4000 in the parameters field, I get:
> 
> qqPlot(EmpiricalData$Value, dist="triangle", 3000,5000,4000)
> 
> it produces a plot, but I am not sure that this is correct.
> 
> I have searched for examples, not found anything.  Any help much
> appreciated.
> 
> R. Males
> Cincinnati, Ohio, USA
> 
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