st: Why is some observations lost when specifying bw(1) in xtivreg2

[David Granlund <david.granlund@econ.umu.se>]

I have a sample of 910 observations, 91 groups and 10 years, without any 
missing data. When I estimate a robust fixed effect model the Number of obs 
is correctly reported as 910, but when I also specify bw(1) the Number of 
obs is reported to be 842. Can someone help me with an explanation to this?

Thank you in advance for your help!

Regards,
David Granlund


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