how to refer to a previous value in longitudinal data set

[deerdi]

I am working with a longitudinal data; students received a degree at a certain time; I wonder how I can change all the values to 1 after degree attainment. For example, this is what my data looks like now:

Id     time     award

1       1           .

1        2          .

1       3           1

1       4           .

1        5           .

What I would like to do is to change the two missing values for time=5 and time=6 into 1. Any help is appreciated~!

[Reeza]

Look up the lag function and retain statement.

And all the caveats that surround them

[deerdi]

I did....still have not figured out how to do it....Any ideas?