[R] dbetagen function in mc2d package

Ben Bolker bbolker at gmail.com
Thu May 19 19:05:13 CEST 2011


krusty the klown <alessandrobarbiero <at> libero.it> writes:

> I found this useful package for generalized beta, yet the function that
> calculates its density leaves me puzzled, especially when I plotted it:
> 
> plot(function(y) dbetagen(y,4,1.2,min=0,max=40),xlim=c(0,40))
> 
> The area between the density curve and the x axis does not seem to measure
> 1!!!

  It would help to tell us that this is in the "mc2d" package ...

> integrate(dbetagen,shape1=4,shape2=1.2,min=0,max=40,0,40)
40 with absolute error < 2e-06

  I would suggest that you report this as a bug to the
package maintainers [maintainer("mc2d")].  Seems fairly easy to 
fix for yourself, though -- just scale by the size of the domain (max-min).


  Ben Bolker



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