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Re: st: Running Product Function

 From Yuval Arbel To statalist Subject Re: st: Running Product Function Date Sun, 9 Dec 2012 23:19:45 +0200

```Dear statalisters,

Please ignore my previous e-mails regarding this question

After a short additional search, I found a very nice (and well known)
trick proposed by Nick Cox to address the problem (which, from some
reason did not come to my mind):

bysort group : gen prod = sum(ln(x))
by group : replace prod = exp(prod[_N])

On Sun, Dec 9, 2012 at 11:05 PM, Yuval Arbel <yuval.arbel@gmail.com> wrote:
> P.S. According to stata's help, the details of the author of the
> -prod()- function is:
>
> Philip Ryan
> Department of Public Health
> South Australia
>
>
> On Sun, Dec 9, 2012 at 10:53 PM, Yuval Arbel <yuval.arbel@gmail.com> wrote:
>> Dear Statalisters,
>>
>> I appreciate very much your assistance in the following question:,
>>
>> I'm looking for an equivalent function for -gen y1=sum()- which will
>> calculate running product for each point in time
>>
>> In fact, what I would like to calculate is a running geometric mean
>>
>> Note also that -gen y2=prod()- does not work (i.e., stata does not
>> identify the function). Only -egen y2=prod()- works, but it generates
>> only one product for each panel, and this is not what I need.
>>
>> Finally, I tried the -amean- command,, but it simply gives summary
>> statistics of different means, and it is not a function..
>> --
>> Dr. Yuval Arbel
>> 4 Shaar Palmer Street,
>> Haifa 33031, Israel
>> e-mail1: yuval.arbel@carmel.ac.il
>> e-mail2: yuval.arbel@gmail.com
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
>> *   http://www.stata.com/support/faqs/resources/statalist-faq/
>> *   http://www.ats.ucla.edu/stat/stata/
>
>
>
> --
> Dr. Yuval Arbel
> 4 Shaar Palmer Street,
> Haifa 33031, Israel
> e-mail1: yuval.arbel@carmel.ac.il
> e-mail2: yuval.arbel@gmail.com

--
Dr. Yuval Arbel