Bookmark and Share

Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: what is -group()-? [Was: Re: st: Extract and save R2 as a variable from looping regressions]


From   Robert Picard <picard@netbox.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: what is -group()-? [Was: Re: st: Extract and save R2 as a variable from looping regressions]
Date   Thu, 24 Oct 2013 15:26:20 -0400

Thanks to both for the history of -group()-. It would be nice if
version control was used to disallow functions that go undocumented.
There is precedent for this, e.g. -norm()- is not recognized if
version is 10 or higher.

On Thu, Oct 24, 2013 at 2:03 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> I overlooked an earlier reply by Phil Schumm, which shows that I gave
> a better answer in 2007:
>
> http://www.stata.com/statalist/archive/2007-03/msg00406.html
> Nick
> njcoxstata@gmail.com
>
>
> On 24 October 2013 18:50, Nick Cox <njcoxstata@gmail.com> wrote:
>> I needed to unearth some old manuals to be sure of this.
>>
>> -group()- is now, and long has been, an undocumented function.
>>
>> In ancient manuals, -group()- is explained as producing as nearly
>> equal-sized subsamples as possible. Its operation is seen at its
>> simplest like this:
>>
>> . clear
>>
>> . set obs 10
>> obs was 0, now 10
>>
>> . gen group = group(2)
>>
>> . l
>>
>>      +-------+
>>      | group |
>>      |-------|
>>   1. |     1 |
>>   2. |     1 |
>>   3. |     1 |
>>   4. |     1 |
>>   5. |     1 |
>>      |-------|
>>   6. |     2 |
>>   7. |     2 |
>>   8. |     2 |
>>   9. |     2 |
>>  10. |     2 |
>>      +-------+
>>
>> What it does when given e.g. a variable as argument was not
>> documented, so far as I can find out.
>>
>> Nick
>>
>>
>> njcoxstata@gmail.com
>>
>>
>> On 1 October 2013 18:23, Robert Picard <picard@netbox.com> wrote:
>>>>  . gen gr_compIDmofd=group (companyID mofd)
>>>>
>>>> is illegal. You must have used -egen-
>>>
>>> Curiously, using -group()- with -generate- does not throw an error but
>>> I have no idea what it's supposed to do. I can't find anything in the
>>> help files about it either.
>>>
>>> sysuse auto
>>> gen g = group(turn)
>>>
>>> Does anyone know what it does?
>>>
>>> Robert
>>>
>>> *
>>> *   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/
> *
> *   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/
*
*   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/


© Copyright 1996–2018 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   Site index