st: Fill in values for year in an unbalanced panel with known order

[Fernando Luco <flucoestatalist@gmail.com>]

Hi all,

I'm trying to fill in the year of observations for which I know the
month and because of the order, I have no doubt about the year.
However, the year was not recorded. In particular, the data looks as
follows

id year month
1 1988 5
1 . 6
1 . 7
1 . 8
1 . 9
1 . 10
1 . 11
1 . 12
1 . 1
1 1989 2
1 1989 3
1 . 4
2 . 3
2 1989 4
2 1989 5
2 . 6
2 . 7
2 . 8
2 1989 9
2 . 10
2 . 11
2 . 12
2 . 1
2 1990 2
2 . 3

So, it is an unbalanced panel, that for each id might start and end at
a different year month combination, and I know that the order of the
observations within id is correct, so I'm sure that the first
observation for id==2 is of 1989 while the second observation that has
id==2 and month==3 (the last observation in the example) corresponds
to 1990. The main complication is that for some people I might have a
gap of more than one year between observations, which has made things
difficult. I would like to use the structure of the data to fill in
the data for year.

Any ideas?

Thanks,

Fernando
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