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Re: st: standardizing scores by cohort


From   Paul Byatta <paulbyatta@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: standardizing scores by cohort
Date   Wed, 24 Apr 2013 15:21:12 +0300

thanks, a lot.

On Wed, Apr 24, 2013 at 2:32 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> Statalist software here can't represent the equals sign = in your post
> correctly. I guess that, contrary to request, you are not sending
> plain text to the list.
>
> That aside
>
> egen mean_math = mean(math), by(yoa)
> egen sd_math = sd(math), by(yoa)
> gen std_math = (math - mean_math) / sd_math
>
> should be simpler than the dreaded alternative. Note that a -by()-
> option is supported, although not documented, by -egen-'s -mean()- and
> -sd()- functions, but your indicated syntax
>
> ... by yoa
>
> certainly would not work.
>
> Nick
> njcoxstata@gmail.com
>
> On 24 April 2013 12:15, Paul Byatta <paulbyatta@gmail.com> wrote:
>
>> I am trying to standardize raw
>> scores for several cohorts of students based on year of admission to high
>> school.
>>
>> My data looks like this
>>
>>
>> StudentID    Year of                   math
>>                    Admission (yoa)
>>
>> 1                  2004                     78
>> 2                  2004                     83
>> 3                  2004                     99
>> 4                  2005                      58
>> 5                  2005                     68
>> 6                  2005                     67
>> 7                  2006                     87
>> 8                  2006                     75
>> 9                  2006                    56
>>
>> It would have been easier to use
>>
>>
>> egen std_math =3D std(math) by yoa
>>
>> But then egen doesn=92t go with =93by=94 in this case.
>>
>> Anybody with a suggestion of how standardize the scores without having to
>> through the long process that is (below) and combining the generated
>> variables to get std_math?
>>
>>
>>
>> egen std_math4 =3D std(math) if yoa=3D=3D2004
>> egen std_math5 =3D std(math) if yoa=3D=3D2005
>> egen std_math6 =3D std(math) if yoa=3D=3D2006
>>
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