[R] Plotting Bi-Gamma Distribution

[Ben Bolker]

Gundala Viswanath <gundalav <at> gmail.com> writes:

> 
> Hi all,
> 
> I've tried to plot a vector which has two peaks in the density.
> This link shows the figure.
> 
> http://docs.google.com/View?docid=dcvdrfrh_1dk9r2rc7
> 
> The red line is normal curve and green line is gamma curve.
> Notice that red line can correctly fit the histogram that has two peaks
> (i.e. red curve also has two peaks).
> 
> But the gamma curve there only has one curve.
> 
> Is there a way I can fit the gamma function such that it also
> yields two peaks?
> 

  The gamma distribution is always unimodal (i.e.,
a single peak).  (You call the red line a "normal
curve", but it's really a nonparametric density
estimate.)  You might want to search the list and
the available packages for "mixture models", which
are a standard way of fitting multimodal distributions ...

  Ben Bolker