[R-sig-eco] probability distribution for zero-inflated, right skewed data

[Augustine, Benjamin C]

I recently analyzed a heavily right-skewed distribution with 56% 0's using a zero adjusted inverse Gaussian distribution in the package GAMLSS.  You might try that, or I'm sure you can use that distribution in JAGS.  There is some literature on using this distribution to model insurance claims.

________________________________________
From: r-sig-ecology-bounces at r-project.org [r-sig-ecology-bounces at r-project.org] on behalf of Bob O'Hara [bohara at senckenberg.de]
Sent: Monday, June 16, 2014 8:29 AM
To: r-sig-ecology at r-project.org
Subject: Re: [R-sig-eco] probability distribution for zero-inflated, right skewed data

On 16/06/14 13:57, Johannes Björk wrote:
> Dear all,
>
> Im looking into how to fit a GLM model (Im using rjags) with data that are heavily right skewed. In addition, some variables also zero-inflated. The data are species area distribution measured as "total area (km^2)" which is subsetted into "area in tropical zone" and "area in temperate zone". The last two variables contain zeros.
>
> I have google zero-inflated models... and most that come up is "zero-inflated negative binomial" and zero-inflated negative poisson" for count data. I reckon I cannot use any of these distributions since my variables are not discrete.
>
> Any pointer to which distribution(s) that might fit this kind of data would be much appreciated.
I think a Tweedie distribution is sometimes used, but that always makes
me think of escaping chickens. Recently this was published, which might
also be useful:
<http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12122/abstract>.
They used BUGS, so you could ask them if the code is available. Even if
it isn't, it shouldn't be too difficult to code up.

Bob

--

Bob O'Hara

Biodiversity and Climate Research Centre
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