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# Re: st: Insert new observation by group

 From Fernando Luco To statalist@hsphsun2.harvard.edu Subject Re: st: Insert new observation by group Date Wed, 2 Nov 2011 16:30:53 -0500

```Thanks for quick response Austin. It was just what I was trying to do.

On Wed, Nov 2, 2011 at 4:22 PM, Austin Nichols <austinnichols@gmail.com> wrote:
> Fernando Luco <flucoestatalist@gmail.com> :
>
> clear
> input group y  x
> 1       1       10
> 1       2       10
> 1       2       10
> 2       3       8
> 2       1       8
> end
> g obs=_n
> bys group x: g e=1+(_N==_n)
> expand e
> bys group x (obs): replace y=. if _n==_N
> by group x: g sumy=sum(y)
> replace y=x-sumy if mi(y)
> list, sepby(group)
>
>
> On Wed, Nov 2, 2011 at 5:13 PM, Fernando Luco <flucoestatalist@gmail.com> wrote:
>> Dear all,
>>
>> I'm trying to create a new observation for each group in my data, but
>> I haven't been able to do so. I tried using -ingap- but didn't work
>> because
>> it inserts the new observation at the top of the group or after the
>> first observation.
>> My data looks as follows:
>>
>> group y  x
>> 1       1       10
>> 1       2       10
>> 1       2       10
>> 2       3       8
>> 2       1       8
>>
>> What I want is to insert a new observation at the end of each group,
>> and this observation must be the difference between "x" (in my case
>> this is 10 for group one and 8 for group two) and the sum of "y"
>> (6 for group one and 3 for group two). So, the idea is that the final
>> dataset should look as follows
>>
>> group y x
>> 1       1       10
>> 1       2       10
>> 1       2       10
>> 1      5       10
>> 2       3       8
>> 2       1       8
>> 2      4       8
>>
>> Any ideas? Thanks,
>>
>> Fernando
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
>> *   http://www.stata.com/support/statalist/faq
>> *   http://www.ats.ucla.edu/stat/stata/
>>
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```