How to Count the Number of the Students Having Grade Retention in a Dataset in Stata Code?

[smith Jason]

As the title suggested, I would like to count the number of the students who had grade retention in K-12 system. For example, I want to know how many students who made normal grade progression, how many students who had one-time grade retention, how many students who had two-time grade retentions....etc. The dataset is structured in long format below,
*Simulated dataset.
clear
input byte (id grade)
1 1
1 2
1 2
1 3
1 4
1 4
1 4
1 4
1 5
1 6
1 6
2 1
2 2
2 3
2 4
2 4
2 5
2 5
2 6
2 6
2 6
2 7
3 1
3 2
3 3
3 4
3 5
3 6
3 7
4 1
4 1
4 2
4 3
4 4
4 5
4 6
5 1
5 2
5 3
5 4
5 5
5 5
6 1
6 2
6 3
6 4
6 4
6 5
7 1
7 2
7 3
7 3
7 5
7 6
7 7
end
Thank you for your help!

[Nick Cox]

bysort id grade : gen repeat = _n > 1 

by id: egen num_repeats = total(repeat)

You also have students who skipped grades as well.

bysort id (grade) :: gen skip = inrange(grade - grade{_n-1], 2, .) 
by id : egen num_skips = total(skip)

[smith Jason]

Thank you!

[smith Jason]

bysort id grade : gen repeat = _n > 1

by id: egen num_repeats = total(repeat)

You also have students who skipped grades as well.

bysort id (grade) :: gen skip = inrange(grade - grade{_n-1], 2, .)
by id : egen num_skips = total(skip)

Thanks for your response.
If I want to know the distribution about how many students who had grade retention by grade, how could I write Stata code?
Thank you!

[Nick Cox]

See the help for the tag() function under egen.

[smith Jason]

bys id grade : gen repeat = _n > 1
egen tag = tag(grade)
egen tags = total(repeat), by(grade)

It seems that the code above can provide the answer after consulting the resources you mentioned. However, I noticed that the results obtained with the code is presented by total times instead of by person, because one person might have more than one-time grade retention. I really don't know how to develop the code further. Any hints or thoughts?
Thank you for your help!

[Nick Cox]

See if this gets you closer to what you want. I used the data example in #1.

. bysort id grade : gen repeats = _n > 1 

. egen num_repeats = total(repeats), by(id)

. 
. egen tag_id = tag(id)  

. 
. tab num_repeats if tag_id 

num_repeats |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |          1       14.29       14.29
          1 |          4       57.14       71.43
          4 |          1       14.29       85.71
          5 |          1       14.29      100.00
------------+-----------------------------------
      Total |          7      100.00

. 
. egen num_repeats_grade = total(repeats), by(id grade)

. 
. egen tag_id_grade = tag(id grade)

. 
. count if repeats 
  13

. 
. tab num_repeats_grade grade if tag_id_grade 

num_repeat |                                    grade
   s_grade |         1          2          3          4          5          6          7 |     Total
-----------+-----------------------------------------------------------------------------+----------
         0 |         6          6          6          3          5          3          3 |        32 
         1 |         1          1          1          2          2          1          0 |         8 
         2 |         0          0          0          0          0          1          0 |         1 
         3 |         0          0          0          1          0          0          0 |         1 
-----------+-----------------------------------------------------------------------------+----------
     Total |         7          7          7          6          7          5          3 |        42 

. 
. list, sepby(id)

     +----------------------------------------------------------------+
     | id   grade   repeats   num_re~s   tag_id   num_re~e   tag_id~e |
     |----------------------------------------------------------------|
  1. |  1       1         0          5        1          0          1 |
  2. |  1       2         0          5        0          1          1 |
  3. |  1       2         1          5        0          1          0 |
  4. |  1       3         0          5        0          0          1 |
  5. |  1       4         0          5        0          3          1 |
  6. |  1       4         1          5        0          3          0 |
  7. |  1       4         1          5        0          3          0 |
  8. |  1       4         1          5        0          3          0 |
  9. |  1       5         0          5        0          0          1 |
 10. |  1       6         0          5        0          1          1 |
 11. |  1       6         1          5        0          1          0 |
     |----------------------------------------------------------------|
 12. |  2       1         0          4        1          0          1 |
 13. |  2       2         0          4        0          0          1 |
 14. |  2       3         0          4        0          0          1 |
 15. |  2       4         0          4        0          1          1 |
 16. |  2       4         1          4        0          1          0 |
 17. |  2       5         0          4        0          1          1 |
 18. |  2       5         1          4        0          1          0 |
 19. |  2       6         0          4        0          2          1 |
 20. |  2       6         1          4        0          2          0 |
 21. |  2       6         1          4        0          2          0 |
 22. |  2       7         0          4        0          0          1 |
     |----------------------------------------------------------------|
 23. |  3       1         0          0        1          0          1 |
 24. |  3       2         0          0        0          0          1 |
 25. |  3       3         0          0        0          0          1 |
 26. |  3       4         0          0        0          0          1 |
 27. |  3       5         0          0        0          0          1 |
 28. |  3       6         0          0        0          0          1 |
 29. |  3       7         0          0        0          0          1 |
     |----------------------------------------------------------------|
 30. |  4       1         0          1        1          1          1 |
 31. |  4       1         1          1        0          1          0 |
 32. |  4       2         0          1        0          0          1 |
 33. |  4       3         0          1        0          0          1 |
 34. |  4       4         0          1        0          0          1 |
 35. |  4       5         0          1        0          0          1 |
 36. |  4       6         0          1        0          0          1 |
     |----------------------------------------------------------------|
 37. |  5       1         0          1        1          0          1 |
 38. |  5       2         0          1        0          0          1 |
 39. |  5       3         0          1        0          0          1 |
 40. |  5       4         0          1        0          0          1 |
 41. |  5       5         0          1        0          1          1 |
 42. |  5       5         1          1        0          1          0 |
     |----------------------------------------------------------------|
 43. |  6       1         0          1        1          0          1 |
 44. |  6       2         0          1        0          0          1 |
 45. |  6       3         0          1        0          0          1 |
 46. |  6       4         0          1        0          1          1 |
 47. |  6       4         1          1        0          1          0 |
 48. |  6       5         0          1        0          0          1 |
     |----------------------------------------------------------------|
 49. |  7       1         0          1        1          0          1 |
 50. |  7       2         0          1        0          0          1 |
 51. |  7       3         0          1        0          1          1 |
 52. |  7       3         1          1        0          1          0 |
 53. |  7       5         0          1        0          0          1 |
 54. |  7       6         0          1        0          0          1 |
 55. |  7       7         0          1        0          0          1 |
     +----------------------------------------------------------------+

.

[smith Jason]

Thank you!