Hi,

I have a large data seg, where data has been collected (for the same individuals) over three separate rounds. One of the variables is fixed (sex), but is only registrered in round 1 and 3 (not round 2).

How can I transfer the fixed data to round 2?

Right now it looks like this:

ID round sex

1 1 1

1 2 .

1 3 1

2 1 1

2 2 .

2 3 1

3 1 0

3 2 .

3 3 0

I want this:

ID round sex

1 1 1

1 2 1

1 3 1

2 1 1

2 2 1

2 3 1

3 1 0

3 2 0

3 3 0

Since the variable is always present for the first case for a given ID, you can just execute

if missing(sex) sex = lag(sex).