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Re: st: How to Calculate A Variable of Maximum Values up to each of the 114 periods in my sample?


From   Yuval Arbel <yuval.arbel@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: How to Calculate A Variable of Maximum Values up to each of the 114 periods in my sample?
Date   Fri, 14 Dec 2012 19:25:00 +0200

Thanks very much Nick and Ryan. Ryan's set of two commands worked fine

On Fri, Dec 14, 2012 at 7:19 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> Getting the maximum so far is an FAQ on the Stata website. See also a
> function in -egenmore- (SSC).
>
> Nick
>
>
> On 14 Dec 2012, at 16:53, Yuval Arbel <yuval.arbel@gmail.com> wrote:
>
>> Dear Statalisters,
>>
>> I am trying to generate a variable, which will give me the maximum
>> value of another variable (reduct_per) up to each of the 114 periods
>> in my sample.
>>
>> Note that the function -max- works only with -egen-, namely it creates
>> a constant maximum, and not a running maximum..
>>
>> I therefore wrote the following set of commands:
>>
>> by appt: egen y=max(reduct_per)
>> by appt: gen max=reduct_per if time_index==0
>> by appt: replace max=reduct_per if reduct_per==y
>> by appt: replace max=reduct_per[_n-1] if reduct_per<=reduct_per[_n-1]
>> & max==. & time_index==1
>> by appt: replace max=reduct_per if max==. & time_index==1
>>
>> by appt: replace max=max[_n-1] if reduct_per<=max[_n-1] & max==. &
>> time_index==2
>> by appt: replace max=reduct_per if max==. & time_index==2
>>
>> by appt: replace max=max[_n-1] if reduct_per<=max[_n-1] & max==. &
>> time_index==3
>> by appt: replace max=reduct_per if max==. & time_index==3
>>
>> by appt: replace max=max[_n-1] if reduct_per<=max[_n-1] & max==. &
>> time_index==4
>> by appt: replace max=reduct_per if max==. & time_index==4
>>
>> by appt: replace max=max[_n-1] if reduct_per<=max[_n-1] & max==. &
>> time_index==5
>> by appt: replace max=reduct_per if max==. & time_index==5
>>
>> by appt: replace max=max[_n-1] if reduct_per<=max[_n-1] & max==. &
>> time_index==6
>> by appt: replace max=reduct_per if max==. & time_index==6
>>
>> and so on. My question is whether there is a more elegant way to
>> generate this variable. More specifically I would like to know
>> whether I need to write a loop, and if so how would I write it so that
>> I don't have to repeat the last two commands for 114
>
> *
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-- 
Dr. Yuval Arbel
School of Business
Carmel Academic Center
4 Shaar Palmer Street,
Haifa 33031, Israel
e-mail1: yuval.arbel@carmel.ac.il
e-mail2: yuval.arbel@gmail.com
*
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*   http://www.stata.com/help.cgi?search
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*   http://www.ats.ucla.edu/stat/stata/


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