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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   Ryan Kessler <ryan.kessler.stata@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 12:12:45 -0500

How about something like this:

input x
10
100
0
400
30
1000
60
end

gen runmax = x
replace runmax = runmax[_n-1] if runmax[_n-1] > runmax[_n] 	///
& !missing(runmax[_n-1])

Ryan

On Fri, Dec 14, 2012 at 11:53 AM, 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 periods
>
> --
> 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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