st: a question on sample after xtabond command

[Le Manh Duc <duc.lemanh@gmail.com>]

Hi all,

I ran a dynamic panel data model using xtabond command on a unbalanced
panel. I got a result with 7395 obs of 1568 groups.

Now I want to produce a correlation table of the variable in my model
using if e(sample). However, I get a correlation table with 9315 obs.
Why the number of obs from e(sample) is different from the one I got
before (7395 obs) ?

The command as below:

*****

xtabond tecdiv L.firmsize L.rdint L.adsint L.capint L.leverage
L.current L.new_q north_america dyear1990-dyear2000 if year>=1989 &
year<=2000, endogenous(Lpdiv, lag(1,.)) endogenous(Lpdiv_sq, lag(1,.))
twostep vce(robust)

corr tecdiv L.firmsize L.rdint L.adsint L.capint L.leverage L.current
L.new_q north_america dyear1990-dyear2000 Lpdiv Lpdiv_sq if e(sample)

*****

Could you give me some suggestion?

Regards,
Duc
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