# st: AW: Computing and allocating time intervals in a wide dataset

 From "Martin Weiss" <[email protected]> To <[email protected]> Subject st: AW: Computing and allocating time intervals in a wide dataset Date Mon, 8 Jun 2009 23:31:18 +0200

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I would advise you to soak up the wisdom of
http://www.stata.com/support/faqs/data/
before proceeding. Most of the time, you will at least get important hints
there...

Also note there are a couple of columns on data management in the SJ
archive:
http://www.stata-journal.com/archives.html

HTH
Martin

-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Thomas Speidel
Gesendet: Montag, 8. Juni 2009 23:25
An: [email protected]
Betreff: st: Computing and allocating time intervals in a wide dataset

I am attempting to compute several time points to calculate the
interval (years) between the start and the end of an activity and to
assign that interval to its relevant age group.  For example, given
the following dataset:

id   activity   start   stop
1          1       6     15
1          2      22     25
1          3      15     16
1          4      22     28
1          5      30      .
1          6       .      .
2          1      53     69
2          2      69     79

I am trying to derive the following:

id   activity   start   stop   grp_0_17   grp_1~24   grp_2~44
grp_4~64   grp_6~81
1          1       6     15          9          0          0
0          0
1          2      22     25          0        2.5         .5
0          0
1          3      15     16          1          0          0
0          0
1          4      22     28          0        2.5        3.5
0          0
1          5      30      .          0          0          1
0          0
1          6       .      .          .          .          .
.          .
2          1      53     69          0          0          0
11.5        4.5
2          2      69     79          0          0          0
0         10

The age groups are:
[0.5, 17.5]
[17.6, 24.5]
[24.6, 44.5]
[44.6, 64.5]
[64.6, 81]

If the dataset was in long format as above, it would not be terribly
hard. To slightly complicate things is the fact that the interval may
need to be correctly allocated when it falls between two or more age
groups.  However, my data is in wide format (single observation per
row) making it a nightmare to even check or troubleshoot my code (I
have 40 activities per id), and the data is so large that I am
reluctant to reshape it.
This is what the dataset above would look like:

id   start1   stop1   start2   stop2   start3   stop3   start4
stop4   start5   stop5   start6   stop6
1        6      15       22      25       15      16       22
28       30       .        .       .
2       53      69       69      79        .       .        .
.        .       .        .       .

-The activities do not necessarily follow a temporal sequence (e.g.
3rd observation on top)
-While the example does not show that, every id has exactly 40
activities, even though many of them may be completing missing.
-Whenever a start is present but its corresponding stop is missing (as
in the 6th obs. on top), it means that at the time of the study the
person was still performing that activity, hence stop would be a
variable called ageref. If start==ageref, then the interval would be
approximated as 1 year.

I would appreciate any feedback on how to best tackle this problem.

Thanks,
Thomas Speidel

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