Selecting rows

[Claudia Meurs]

I would like to select specific rows in a dataset but I don't know how I can do it.
- I have more than one row per person.
- Rows per persons are ordered by record number
- Every person has a variable A which can be 0 or 1

I would like to generate the variable select.
- Select should be 1 for all records of a person following the record for which the variable A is 1
- Select should be 0 for the records of a person for which the variable A is 1 and for the previous record numbers of that person

Person	Record number	Variable A	Select
1	1	0	0
1	2	1	0
1	3	0	1
2	1	1	0
2	2	0	1
2	3	0	1
2	4	0	1
3	1	0	0
3	2	0	0
3	3	1	0
3	4	0	1
3	5	0	1

[Andrew Musau]

* Example generated by -dataex-. For more info, type help dataex
clear
input byte(person recordnumber variablea select)
1 1 0 0
1 2 1 0
1 3 0 1
2 1 1 0
2 2 0 1
2 3 0 1
2 4 0 1
3 1 0 0
3 2 0 0
3 3 1 0
3 4 0 1
3 5 0 1
end

bys person (recordnumber): gen wanted= sum(sum(variablea))>=2

Res.:

. l, sepby(person)

     +------------------------------------------------+
     | person   record~r   variab~a   select   wanted |
     |------------------------------------------------|
  1. |      1          1          0        0        0 |
  2. |      1          2          1        0        0 |
  3. |      1          3          0        1        1 |
     |------------------------------------------------|
  4. |      2          1          1        0        0 |
  5. |      2          2          0        1        1 |
  6. |      2          3          0        1        1 |
  7. |      2          4          0        1        1 |
     |------------------------------------------------|
  8. |      3          1          0        0        0 |
  9. |      3          2          0        0        0 |
 10. |      3          3          1        0        0 |
 11. |      3          4          0        1        1 |
 12. |      3          5          0        1        1 |
     +------------------------------------------------+

.

[Claudia Meurs]

Thank you very much, this was very helpfull.