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 <[email protected]>
To
"[email protected]" <[email protected]>
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 <[email protected]> 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
> [email protected]
>
>
> On 24 October 2013 18:50, Nick Cox <[email protected]> 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
>>
>>
>> [email protected]
>>
>>
>> On 1 October 2013 18:23, Robert Picard <[email protected]> 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/