Calculating percentages within groups

[Abbas Raza]

id	groups	variable%
1	1	50
1	1	50
1	2	25
1	3	23
2	2	100
2	2	100
2	2	100
3	1	100

Hi,

I have dataset having more than 100k observations. I would like to generate a variable that would allow me calculate the percentages of the number of each "groups" within "id".

For example, I would like to generate "variable%" as a percentage of group values within groups i.e. 50% values in id=1 are spanned over group 1, 25% for group 2 and 3 (and so on for every id)

I have tried egen command as: bysort id : egen total_id = count(id) - which allows me to calculate the totals of each id. But I am not able to figure out how to calculate percentages within groups. Any help in this regard would help a lot.

[Abbas Raza]

Could anyone able to help with this? I am completely stuck with this. I have tried to use egen command with serval variations (directly computing proportions, count totals and dividing with each other) but it does not solve within groups problem.

[Marcos Almeida]

You may wish to take a look at this FAQ.

[Thong Nguyen]

Dear Abbas,
You should read the post http://www.stata.com/support/faqs/da...ary-variables/

[Nick Cox]

Abbas:

In #2 you bumped the thread after 42 minutes. For the future please follow advice on bumping in http://www.statalist.org/forums/help#adviceextras #1 .

Otherwise, and noting that 23 is a typo, consider

clear

input id    groups    wanted
1    1    50
1    1    50
1    2    25
1    3    25
2    2    100
2    2    100
2    2    100
3    1    100
end 

bysort id group: gen prop = _N 
by id: replace prop = 100 * prop/_N 

list, sepby(id) 

     +-----------------------------+
     | id   groups   wanted   prop |
     |-----------------------------|
  1. |  1        1       50     50 |
  2. |  1        1       50     50 |
  3. |  1        2       25     25 |
  4. |  1        3       25     25 |
     |-----------------------------|
  5. |  2        2      100    100 |
  6. |  2        2      100    100 |
  7. |  2        2      100    100 |
     |-----------------------------|
  8. |  3        1      100    100 |
     +-----------------------------+