[R-sig-ME] response variable distribution-MCMCglmm

[Paul Buerkner]

Hi Walid,

I am also not aware of any such distribution in MCMCglmm, but you may want
to try out the "hurdle_gamma" or "hurdle_lognormal" family in the brms R
package, to model positive real responses with zero-inflation.

Best,
Paul

2017-06-21 19:57 GMT+02:00 Walid <walidmawass10 at gmail.com>:

> Hello everyone,
>
> I have a question regarding appropriately choosing the distribution for a
> response variable in MCMCglmm in R. My variable is a fitness trait
> calculated from the total lifetime reproductive success of the individual,
> the rate of growth of the population and individual survival (Following
> Method in Moorad(2014)).
>
> The variable we arrived at is inflated at zero and the rest of the values
> (non-integer and non-negative) fall into an almost gaussian distribution
> (descriptively somewhat of a zero inflated Poisson distribution). After
> doing lots of research regarding extended distributions, the best result I
> found was that this variable may follow a Tweedie distribution, more
> specifically a compound Poisson-gamma distribution (through descriptively
> comparing the distributions).
>
> The problem here is that I don't know how to include this in my MCMCglmm
> model, I do not recall if the families of distributions supported in
> MCMCglmm include Tweedie distributions. And if not, I do not know if there
> is a convenient approximation method to accommodate this.
>
> I hope my question fits the general requirement of this list that the
> subject be related to mixed models.
>
> Thank you in advance
>
> --
> Walid Mawass
> Maitrise en Biologie Cellulaire et Moléculaire
> Laboratoire de Génétique des Populations
> Département de Chimie, Biochimie et Physique
> Université du Quebec à Trois-Rivières
> 3351, Boul. des Forges, C.P.500
> Tel. (819)-376-5011 poste 3384
>
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