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Re: st: Accumulated mean and standard deviation


From   Pedro Nakashima <nakashimapedrolist@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Accumulated mean and standard deviation
Date   Sun, 8 Jan 2012 20:34:08 -0200

Thank you Matthew, It worked perfectly!

Best,
Pedro.



2012/1/8 Matthew White <mwhite@poverty-action.org>:
> Hi Pedro,
>
> Again, the mean is just one line:
>
> by day: generate mean = sum(x) / _n
>
> For the SD, I think the most efficient option is to use a program. See
> -help byable-:
>
> program runningsd, byable(recall, noheader)
>        syntax varname, Generate(name)
>        if _byindex() == 1 {
>                confirm new variable `generate'
>                quietly generate `generate' = .
>        }
>
>        if !_by() {
>                local start 1
>                local end = _N
>        }
>        else {
>                local start = _byn1()
>                local end   = _byn2()
>        }
>
>        forvalues i = `start'/`end' {
>           quietly summarize `varlist' in `start'/`i'
>           quietly replace `generate' = r(sd) in `i'
>        }
> end
>
> Then:
>
> by day: runningsd x, generate(sd)
>
> Best,
> Matt
>
> On Sun, Jan 8, 2012 at 3:23 PM, Pedro Nakashima
> <nakashimapedrolist@gmail.com> wrote:
>> Hi guys
>>
>> Unfortunately, I forgot one important point for my analysis.
>>
>> Given that I have the same kind of data for several days and I need to
>> calculate these statistics for each of these days, I have to do
>> something like "bysort days: 'all those commands' "
>>
>> Do you know how can I do that?
>>
>> One more time, best regards
>> Pedro
>>
>> 2012/1/8 Pedro Nakashima <nakashimapedrolist@gmail.com>:
>>> Perfect!
>>>
>>> Thank you Matthew and Sunil!
>>>
>>> Best,
>>> Pedro.
>>>
>>> 2012/1/8 Sunil Kumar <stuff.sunil@googlemail.com>:
>>>> Does this achieve what you want?
>>>>
>>>> gen mean=.
>>>> gen sd=.
>>>>
>>>> local k=_N
>>>> forv i=1/`k' {
>>>> qui su x in  1/`i'
>>>> qui replace mean=r(mean) in `i'
>>>> qui replace sd=r(sd) in `i'
>>>> }
>>>>
>>>> Best,
>>>> Sunil
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>
>
>
> --
> Matthew White
> Data Coordinator
> Innovations for Poverty Action
> 101 Whitney Avenue, New Haven, CT 06510 USA
> +1 434-305-9861
> www.poverty-action.org
>
> *
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