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st: Bias in a zero truncated poisson
From
Laurie Molina <[email protected]>
To
[email protected]
Subject
st: Bias in a zero truncated poisson
Date
Sun, 31 Oct 2010 10:11:35 -0600
Hi all,
My dependent variable is a count data variable that takes only positive values.
I am running:
***
ztp depvar indepvars
predict number
sum depvar
sum number
****
but the mean of depvar is not the same as the mean of number.
On the other hand if i run
******
poisson depvar indepvars
predict number2
sum depvar
sum number2
******
the mean of depvar is the same as the mean of number2.
Why is this happening?
Aren't ztp estimates unbiased estimates?
Thank you all as always...
LM
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