[R] Fitdistrplus and Parameter Constraints

Lorenzo Isella lorenzo.isella at gmail.com
Tue May 23 18:22:00 CEST 2017


Dear All,
In principle it is a simple question, but not idea about how to tackle
it.
Suppose you have a distribution depending on two parameters,
e.g. beta(a,b).
For some reasons, you want to impose
that the two parameters of the beta distribution are identical,
i.e. you want to fit your data to beta(a,a).
For instance

x<-rbeta(1000, 0.1, 0.1)
require(fitdistrplus)

mm<-fitdist(x, "beta",  method = "mge")


is how you would normally fit a sample, but I do not know how to
impose the constrain a=b before the fitting.
Any suggestion is appreciated.
Cheers

Lorenzo



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