### Tuesday, March 21, 2006

## st: RE: RE: FW: zinb help

Hi,

I am seriously sorry nick I wasnt trying to be clever ... but I did go through help and the manuals .. I was looking at the descriptions which does not say that clearly..it says..

zinb estimates a maximum-likelihood zero-inflated negative binomial regression of depvar on varlist,where depvar is a nonnegative count variable.

Of course I didint understand the syntax diagram .. my fault.. but now I understand that Typing [ and ] means the varlist is optional.

So the command will be zinb (var),inflate(var).. is that right?

Thanks Rajesh

This refers to the exchange below.

The syntax diagram for -zinb- makes it clear that independent variables need not be specified: thus -zinb- may be used to fit a distribution to a response (dependent) variable alone.

So, again, do please read the help.

Nick n.j.cox@durham.ac.uk

--------------------------- 28 February 2006 Stata offers many commands for these distributions and others in the same territory.

Please use -help-, -search- and the manual before sending such queries to the list.

> I have a dataset which looks like the one below > > Individual 1 individual 2 > Time count count > 1 0 1 > 2 1 0 > 3 0 0 > 4 0 0 > 5 3 1 > 6 0 0 > 7 1 0 > > Time represents months and count represents the occurance of > an event. I > understand that count might follow a zero inflated poisson > distribution or > a negative binomial distribution. > > Are there any stata command to check if the data fits these > distributions? > (just like we have the shapiro-wilk test for normality.). > > My objective is to see if there is any increase in the counts > between say > period1 (time 1 to 3) and period2 (time 4 to7) for each > individual. And for > all individuals taken together...

---------------------------------------------------------------------------- ----

Rajesh Tharyan > I have asked this question before but got told off... but I > am no closer to > finding an answer... I know there is "nbfit" to fit a > negative binomial > distribution to a single variable by the method of maximum > likelihood. Is > there something similar to fit a zero inflated negative binomial > distribution to a single variable? I found nbvargr which fits > a poisson and > a negbinomial dist to a variable but nothing on zero inflated > distributions. > > The only commands related to zero inflated models I found were zip and > zinb... > > I am sorry if it is still a very dumb question..

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Tag: statalist