Statalist The Stata Listserver


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: Truncating Poisson - using ML


From   "Vimalanand S. Prabhu" <prabhu@unc.edu>
To   statalist@hsphsun2.harvard.edu
Subject   st: Truncating Poisson - using ML
Date   Tue, 29 Aug 2006 19:14:02 -0400

Dear all,

The MLE for poisson function is L= exp(-lambda)Lambda^Y/Y!

I found the following code for poisson on a website (by David Todd) as follows:

program define poisreg2
args lnf theta
quietly replace `lnf' = -exp(`theta') + $ML_y1*(`theta')-lnfact($ML_y1)
end

Now, I want to truncate the distribution. The new MLE function is
L2 = L/prob(y<=ymax).
i.e. divide the likelihood function by prob(y<=ymax).
i.e subtract the log function by CDF_POISSON(lambda,ymax).

For that I need a poisson cumulative distribution function which I am not able to find out.

What is the command for finding a cumulative distribution function? It should use two parameters and should be something like, f= poisson(lambda,ymax)

Thanks,

Prabhu

*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/




© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index