List of values of variable by patient-ID

[Cathrine Christiansen]

Dear stata-community,
I would like to have a list of how many patients that has a certain age, but only counting each patient-ID once.

So I need a list something like
age_2012 age_2019
19 freq 2 18 freq 1
28 freq 1 26 freq 2
32 freq 4 39 freq 4

The reason I need for both 2012 and 2019 is that some of the patients from 2012 has left, and new patients have come into my data-material.

* Example generated by -dataex-. For more info, type help dataex
clear
input byte pasID str2(age_2012 age_2019)
1 "32" "39"
1 "32" "39"
2 "28" "."
2 "28" "."
2 "28" "."
3 "19" "26"
3 "19" "26"
3 "19" "26"
3 "19" "26"
4 "32" "39"
4 "32" "39"
5 "19" "26"
6 "32" "39"
6 "32" "39"
7 "32" "39"
8 "."  "18"
8 "."  "18"
end

I also have the variables "birthyear" and "year".

Thank you, Cathrine

[Andrew Musau]

See

help contract
help egen

preserve
egen tag= tag(pasID)
contract age_2012 age_2019 if tag
l
restore

Res.:

. l

     +-----------------------------+
     | age_2012   age_2019   _freq |
     |-----------------------------|
  1. |        .         18       1 |
  2. |       19         26       2 |
  3. |       28          .       1 |
  4. |       32         39       4 |
     +-----------------------------+

[Nick Cox]

Note also

* Example generated by -dataex-. For more info, type help dataex
clear
input byte pasID str2(age_2012 age_2019)
1 "32" "39"
1 "32" "39"
2 "28" "."
2 "28" "."
2 "28" "."
3 "19" "26"
3 "19" "26"
3 "19" "26"
3 "19" "26"
4 "32" "39"
4 "32" "39"
5 "19" "26"
6 "32" "39"
6 "32" "39"
7 "32" "39"
8 "."  "18"
8 "."  "18"
end

groups age_*

  +---------------------------------------+
  | age_2012   age_2019   Freq.   Percent |
  |---------------------------------------|
  |        .         18       2     11.76 |
  |       19         26       5     29.41 |
  |       28          .       3     17.65 |
  |       32         39       7     41.18 |
  +---------------------------------------+

Naturally you can apply tag() first as well.

groups is now from the Stata Journal and must be installed before it can be used. As I used a simple English word for the command name, the best search is an otherwise unpredictable

. search st0496, entry

Search of official help files, FAQs, Examples, and Stata Journals

SJ-18-1 st0496_1  . . . . . . . . . . . . . . . . . Software update for groups
        (help groups if installed)  . . . . . . . . . . . . . . . .  N. J. Cox
        Q1/18   SJ 18(1):291
        groups exited with an error message if weights were specified;
        this has been corrected

SJ-17-3 st0496  . . . . .  Speaking Stata: Tables as lists: The groups command
        (help groups if installed)  . . . . . . . . . . . . . . . .  N. J. Cox
        Q3/17   SJ 17(3):760--773
        presents command for listing group frequencies and percents and
        cumulations thereof; for various subsetting and ordering by
        frequencies, percents, and so on; for reordering of columns;
        and for saving tabulated data to new datasets

For a fairly quick overview see https://www.statalist.org/forums/for...updated-on-ssc

[Cathrine Christiansen]

Thank you!