You may often use "Beta" to measure the market exposure of your portfolio because it's easy to calculate.Since I have been wondering how much "Beta" change depending on time, more precisely writing, data-set and the period of return time series, I...






![Le Monde puzzle [#739]](http://xianblog.files.wordpress.com/2011/09/lemonde739-e1315153639188.jpg?w=378&h=349)


Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).