probability distribution for zero-inflated, right skewed data
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