st: "imputing" missing observations

["Heather Gold" <heg2001@med.cornell.edu>]

Dear Fellow Listers --

I've been looking all around, asking around, etc, and I can't seem to find 
out how to create new observations within my dataset.

Here are the specifics of my problem:
I have counts of cases by zip code and year (one observation with count for 
each zip, and year). It happened that I ended up with "missing" 
observations if the count of cases was zero in a year, so my data look 
something like this
zip             year    count
06010           1986    1
06010           1987    2
06010           1988    2
06010           1990    7
...

How would I create a new observation for this zipcode in 1989 that has a 
count of 0? I need to be able to create some lagged variables by year and zip.

I appreciate your help.
Thanks,
Heather

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Heather Taffet Gold, PhD 
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