st: xtabond changes in Stata 9

[Allin Cottrell <cottrell@wfu.edu>]

On the page http://www.stata.com/help.cgi?whatsnew
item #48 says: "xtabond produced consistent but inefficient 
estimates when there were gaps in the time series. This has been 
fixed."

Can anyone tell me anything about the details of this?  That is, 
how exactly v9 is extracting more efficient estimates?  Thanks.

--
Allin Cottrell
Department of Economics
Wake Forest University, NC
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