Statistics Seminar: Alan H. Welsh -- Recent Reflections on Extra Zeros in Count Data

Alan H.  Welsh Centre for Mathematics and its Applications The Australian National
University 

Location: Carslaw 173 

Time: 2pm Friday, September 18, 2009 

Title: Recent Reflections on Extra Zeros in Count Data 

Abstract: The simplest way to model count data with extra zeros seems to be to include
an extra spike at the origin, forming effectively a mixture distribution with a
degenerate component.  Nonetheless, there are at least two different ways of forming the
mixture.  It seems not to be widely appreciated that, at least when covariates are
included, two different models result.  In this talk we will describe the two models,
make a detailed comparison of them and discuss the implications for data analysis.