# st: RE: assigning calculated values to other groups (was: Data problem again)

 From "Nick Cox" <[email protected]> To <[email protected]> Subject st: RE: assigning calculated values to other groups (was: Data problem again) Date Fri, 14 Nov 2003 15:04:04 -0000

```Ernest Berkhout replied to Lok Wong

> >I have "area,education,gender,wage"in my dataset...Now I
> want to calculate
> >the mean and GINI coefficient of only male wage by area and
> >education...and assign these values to females in the same
> area-education
> >group..How could I do that?
>
> First, let me point out that you might learn something from
> the collection
> of FAQs on
> http://www.stata.com/support/faqs/
>
> In a quick scan, I think that this one might be of interest to you
> http://www.stata.com/support/faqs/data/weighted.html but
> ofcourse thare may
> be other as well.
>
> Apart from that, your questions sounds like the following
> approach to me:
>
> egen group=(area education)
> levels group
> foreach x of local group  {
>          summ wage if sex=="male" [aw=weight]
>          replace wage = r(mean)
> }

In addition -- and note that Ernest's suggestion
is schematic, and not workable code -- there
is a general "copying down" technique useful
in many problems.

Lok Wong wants to calculate for _males_ and to
copy the results to _females_. An analogue of
that with the auto data is to calculate
for foreign cars, and copy to domestic.

. bysort rep78 : egen meanmpg = mean(mpg) if foreign
(52 missing values generated)

. sort rep78 meanmpg

. list  rep78 meanmpg foreign

+-----------------------------+
| rep78    meanmpg    foreign |
|-----------------------------|
1. |     1          .   Domestic |
2. |     1          .   Domestic |
3. |     2          .   Domestic |
4. |     2          .   Domestic |
5. |     2          .   Domestic |
|-----------------------------|
6. |     2          .   Domestic |
7. |     2          .   Domestic |
8. |     2          .   Domestic |
9. |     2          .   Domestic |
10. |     2          .   Domestic |
|-----------------------------|
11. |     3   23.33333    Foreign |
12. |     3   23.33333    Foreign |
13. |     3   23.33333    Foreign |
14. |     3          .   Domestic |
15. |     3          .   Domestic |
|-----------------------------|
16. |     3          .   Domestic |
17. |     3          .   Domestic |
18. |     3          .   Domestic |
19. |     3          .   Domestic |
20. |     3          .   Domestic |
|-----------------------------|
21. |     3          .   Domestic |
22. |     3          .   Domestic |
23. |     3          .   Domestic |
24. |     3          .   Domestic |
25. |     3          .   Domestic |
|-----------------------------|
26. |     3          .   Domestic |
27. |     3          .   Domestic |
28. |     3          .   Domestic |
29. |     3          .   Domestic |
30. |     3          .   Domestic |
|-----------------------------|
31. |     3          .   Domestic |
32. |     3          .   Domestic |
33. |     3          .   Domestic |
34. |     3          .   Domestic |
35. |     3          .   Domestic |
|-----------------------------|
36. |     3          .   Domestic |
37. |     3          .   Domestic |
38. |     3          .   Domestic |
39. |     3          .   Domestic |
40. |     3          .   Domestic |
|-----------------------------|
41. |     4   24.88889    Foreign |
42. |     4   24.88889    Foreign |
43. |     4   24.88889    Foreign |
44. |     4   24.88889    Foreign |
45. |     4   24.88889    Foreign |
|-----------------------------|
46. |     4   24.88889    Foreign |
47. |     4   24.88889    Foreign |
48. |     4   24.88889    Foreign |
49. |     4   24.88889    Foreign |
50. |     4          .   Domestic |
|-----------------------------|
51. |     4          .   Domestic |
52. |     4          .   Domestic |
53. |     4          .   Domestic |
54. |     4          .   Domestic |
55. |     4          .   Domestic |
|-----------------------------|
56. |     4          .   Domestic |
57. |     4          .   Domestic |
58. |     4          .   Domestic |
59. |     5   26.33333    Foreign |
60. |     5   26.33333    Foreign |
|-----------------------------|
61. |     5   26.33333    Foreign |
62. |     5   26.33333    Foreign |
63. |     5   26.33333    Foreign |
64. |     5   26.33333    Foreign |
65. |     5   26.33333    Foreign |
|-----------------------------|
66. |     5   26.33333    Foreign |
67. |     5   26.33333    Foreign |
68. |     5          .   Domestic |
69. |     5          .   Domestic |
70. |     .         14    Foreign |
|-----------------------------|
71. |     .          .   Domestic |
72. |     .          .   Domestic |
73. |     .          .   Domestic |
74. |     .          .   Domestic |
+-----------------------------+

Once we've got things in that sort order,
we can copy down from the non-missings
to the missings. We do this _within_
appropriate groups:

. bysort rep78 : replace meanmpg = meanmpg[_n-1] if mi(meanmpg)

. list  rep78 meanmpg foreign

+-----------------------------+
| rep78    meanmpg    foreign |
|-----------------------------|
1. |     1          .   Domestic |
2. |     1          .   Domestic |
3. |     2          .   Domestic |
4. |     2          .   Domestic |
5. |     2          .   Domestic |
|-----------------------------|
6. |     2          .   Domestic |
7. |     2          .   Domestic |
8. |     2          .   Domestic |
9. |     2          .   Domestic |
10. |     2          .   Domestic |
|-----------------------------|
11. |     3   23.33333    Foreign |
12. |     3   23.33333    Foreign |
13. |     3   23.33333    Foreign |
14. |     3   23.33333   Domestic |
15. |     3   23.33333   Domestic |
|-----------------------------|
16. |     3   23.33333   Domestic |
17. |     3   23.33333   Domestic |
18. |     3   23.33333   Domestic |
19. |     3   23.33333   Domestic |
20. |     3   23.33333   Domestic |
|-----------------------------|
21. |     3   23.33333   Domestic |
22. |     3   23.33333   Domestic |
23. |     3   23.33333   Domestic |
24. |     3   23.33333   Domestic |
25. |     3   23.33333   Domestic |
|-----------------------------|
26. |     3   23.33333   Domestic |
27. |     3   23.33333   Domestic |
28. |     3   23.33333   Domestic |
29. |     3   23.33333   Domestic |
30. |     3   23.33333   Domestic |
|-----------------------------|
31. |     3   23.33333   Domestic |
32. |     3   23.33333   Domestic |
33. |     3   23.33333   Domestic |
34. |     3   23.33333   Domestic |
35. |     3   23.33333   Domestic |
|-----------------------------|
36. |     3   23.33333   Domestic |
37. |     3   23.33333   Domestic |
38. |     3   23.33333   Domestic |
39. |     3   23.33333   Domestic |
40. |     3   23.33333   Domestic |
|-----------------------------|
41. |     4   24.88889    Foreign |
42. |     4   24.88889    Foreign |
43. |     4   24.88889    Foreign |
44. |     4   24.88889    Foreign |
45. |     4   24.88889    Foreign |
|-----------------------------|
46. |     4   24.88889    Foreign |
47. |     4   24.88889    Foreign |
48. |     4   24.88889    Foreign |
49. |     4   24.88889    Foreign |
50. |     4   24.88889   Domestic |
|-----------------------------|
51. |     4   24.88889   Domestic |
52. |     4   24.88889   Domestic |
53. |     4   24.88889   Domestic |
54. |     4   24.88889   Domestic |
55. |     4   24.88889   Domestic |
|-----------------------------|
56. |     4   24.88889   Domestic |
57. |     4   24.88889   Domestic |
58. |     4   24.88889   Domestic |
59. |     5   26.33333    Foreign |
60. |     5   26.33333    Foreign |
|-----------------------------|
61. |     5   26.33333    Foreign |
62. |     5   26.33333    Foreign |
63. |     5   26.33333    Foreign |
64. |     5   26.33333    Foreign |
65. |     5   26.33333    Foreign |
|-----------------------------|
66. |     5   26.33333    Foreign |
67. |     5   26.33333    Foreign |
68. |     5   26.33333   Domestic |
69. |     5   26.33333   Domestic |
70. |     .         14    Foreign |
|-----------------------------|
71. |     .         14   Domestic |
72. |     .         14   Domestic |
73. |     .         14   Domestic |
74. |     .         14   Domestic |
+-----------------------------+

More on the principle at
http://www.stata.com/support/faqs/data/missing.html

Nick
[email protected]

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