st: Re: expanding obs, then changing values based on that

[Michael Costello <michaelavcostello@gmail.com>]

Disregard, I solved it!

I created a variable that counted all the teachers with the same
teacher_id, then used that value to run a substring command which
picked out the exact location in my string that I needed.  No repeats!
 Thanks for helping me think things though!

-Michael

--
Michael Costello
Mathematics & Statistics Teacher, Bethesda-Chevy Chase High School
Intern, RTI International
202-246-1627

"To call in the statistician after the experiment is done may be no
more than asking him to perform a post-mortem examination: he may be
able to say what the experiment died of."  -Sir Ronald Aylmer Fisher,
FRS



On Fri, May 20, 2011 at 11:44 PM, Michael Costello
<michaelavcostello@gmail.com> wrote:
> Statlisters,
> I have a dataset with a variable that asks teachers which section they
> teach.  The options are sections a though e, and more than one answer
> is allowed.  Thus:
> teacher_id    var_a   var_b   var_c   var_d   var_e
> 1             1       0       0       0       0
> 2             1       1       1       0       0
> 3             1       0       0       1       1
> 4             1       0       0       1       0
> I need to duplicate any observation that has a 1 for more than one of
> var_a-var_e.  So I did:
> egen var_total=rowtotal(var_a-var_e)
> expand var_total
> sort teacher_id
> Now, for teacher #2 above for example, I need to assign one (and only
> one?) of her three observations var_a=1, the second var_b=1 and the
> third var_c=1.  This way I can create a new variable, "section" and
> have observation for each section.  It would look like this in the
> end:
> teacher_id  section
> 1           a
> 2           a
> 2           b
> 2           c
> 3           a
> 3           d
> 3           e
> 4           a
> 4           d
> I tried to create a concatenated variable so that I could assign "a"
> if the first number in the concatenated string (from the first table
> above) ==1, "b" if the second number were ==1, etc.  The problem is
> that I cannot figure out how to only change the second observation
> within one teach_id number.  Stated differently, it's changing all,
> not cycling though to the next observation.
> I'm not sure if this is making sense, but if you have ideas, please let me know.
> -Michael
>
> --
> Michael Costello
> Mathematics & Statistics Teacher, Bethesda-Chevy Chase High School
> Intern, RTI International
> 202-246-1627
> "To call in the statistician after the experiment is done may be no
> more than asking him to perform a post-mortem examination: he may be
> able to say what the experiment died of."  -Sir Ronald Aylmer Fisher,
> FRS
>

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