probability distribution for zero-inflated, right skewed data
Definitely looks promising. Thanks Bob!
On Jun 16, 2014, at 2:29 PM, Bob O'Hara wrote:
On 16/06/14 13:57, Johannes Bj?rk 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 Senckenberganlage 25 D-60325 Frankfurt am Main, Germany Tel: +49 69 7542 1863 Mobile: +49 1515 888 5440 WWW: http://www.bik-f.de/root/index.php?page_id=219 Blog: http://blogs.nature.com/boboh Journal of Negative Results - EEB: www.jnr-eeb.org
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