How To Fill Missing Values

[David Laid]

Hi all,

I'm currently working a dataset in which some of the values of the variable are missing. I'm unable to share the data, therefore, I'm giving an example below for a context. For example, as you can see that IDs are recorded repeatedly with visits but values are missing for IDs. How can I fill those missing values according to each ID once a value of Visit is created. In other words, (example below) I want to fill all missing values of ID (1)= 10. And for all ID (4) = 20 , for all ID (6) = 20 and so on. Please note that there are only two values for Visit variable. I would be very grateful if anybody could help me with a particular code on this problem. Please let me know if you need further clarification. Thank you so much.


Variables:

ID: Visit:
1 10
1 10
1
2 10
2
2
3
4 20
4
4
4
5 10
5
6
6
6 20
6
6

[William Lisowski]

Perhaps this will start you in a useful direction.

* Example generated by -dataex-. For more info, type help dataex
clear
input byte(id visit)
1 10
1 10
1  .
2 10
2  .
2  .
3  .
4 20
4  .
4  .
4  .
5 10
5  .
6  .
6  .
6 20
6  .
6  .
end
egen v = max(visit), by(id)
replace visit = v if visit==.
list, sepby(id)

. list, sepby(id)

     +-----------------+
     | id   visit    v |
     |-----------------|
  1. |  1      10   10 |
  2. |  1      10   10 |
  3. |  1      10   10 |
     |-----------------|
  4. |  2      10   10 |
  5. |  2      10   10 |
  6. |  2      10   10 |
     |-----------------|
  7. |  3       .    . |
     |-----------------|
  8. |  4      20   20 |
  9. |  4      20   20 |
 10. |  4      20   20 |
 11. |  4      20   20 |
     |-----------------|
 12. |  5      10   10 |
 13. |  5      10   10 |
     |-----------------|
 14. |  6      20   20 |
 15. |  6      20   20 |
 16. |  6      20   20 |
 17. |  6      20   20 |
 18. |  6      20   20 |
     +-----------------+