Monthly Archives: March 2015

Dealing with overdispersion in ecological data

Jonathan Rhodes describes his new book chapter on “Dealing with overdispersion in ecological data”.

Rhodes Conservation Research Group

Check out my chapter in Gordon Fox, Simoneta Negrete-Yankelevich, and Vinicio Sosa’s new ecological statistics book.

MATLAB Handle Graphics Zero-inflated data

Ecological data rarely meet the assumptions of the standard probably distributions that are used in most statistical models – in particular, our data are often overdispersed (that is, the variance of our data is higher than can be acommodated by standard distributions). One particularly common source of overdispersion is zero-inflation where our data have too many zeros. See a previous paper of ours on zero-inflation here. But how do we deal with these types of non-standard data issues!

In this chapter I address this by focussing on how we can use mixture models (which are combinations of two or more probability distributions) to deal with the general issue of overdispersion. I demonstrate that, not only can mixture models help to account for overdispersion, but they are also very useful for…

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