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
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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