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]

From |
Partho Sarkar <[email protected]> |

To |
[email protected] |

Subject |
Re: st: how can i make my loop run faster? |

Date |
Tue, 20 Sep 2011 10:03:04 +0530 |

```
I guess Stefano might have solved his problem by now, but just to
complete this, here is a post by Brian R. Landy from an older thread
which gives the complete code for -rolling-, including merging the
results files.
http://www.stata.com/statalist/archive/2009-09/msg01239.html
The thread also points out the speed problems with rolling for panel data.
P.Sarkar
On Mon, Sep 19, 2011 at 10:18 PM, Partho Sarkar
<[email protected]> wrote:
> Sorry, I made a mistake in that post. -rolling- will only work on one
> panel at a time, So you could do :
>
> levelsof firm==`z', local(firms)
> foreach j of local firms {
> rolling _b if firm=`j',w(20) saving(tryroll`j'): regress y x
> }
>
> Partho
>
> On Mon, Sep 19, 2011 at 10:02 PM, Partho Sarkar
> <[email protected]> wrote:
>> I think the -rolling- time series command can help do this. E.g.
>> once you a) tsset the panel as before, and b) sort the dataset by
>> -sort panelvar datevar-
>>
>> rolling _b,w(20) saving(tryroll): regress y x
>>
>> would divide up your entire time span into overlapping windows of
>> width 20, run a regression for each panel in each window, and save the
>> panel ids, the start & end of each window, and the regression
>> coefficients, in a Stata data file called "tryroll".
>>
>> See -help rolling- and the manual entry for details & examples. Given
>> your special requirements, you will probably have to do this in 2 or
>> more steps, and manipulate the results further to get exactly what you
>> want.
>>
>> Partho
>>
>> On Mon, Sep 19, 2011 at 8:20 PM, Stefano Rossi <[email protected]> wrote:
>>> Partho,
>>>
>>> Many thanks for this, it is very helpful.
>>>
>>> This raises one question, though: a crucial part of my procedure is that I need to run regressions only on 12 observations for each firm-period pair; that is, if a firm i has data back to period t=-50, say, I still have to run the regression only on the 12 observations from -1 to -12, ignoring all others. This worked well with my loop, but I do not see readily how to do this with statsby. Can you please advise?
>>>
>>> Best,
>>>
>>> Stefano
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: [email protected] [mailto:[email protected]] On Behalf Of Partho Sarkar
>>> Sent: Monday, September 19, 2011 1:06 AM
>>> To: [email protected]
>>> Subject: Re: st: how can i make my loop run faster?
>>>
>>> Stefano
>>>
>>> You don't seem to be actually making any use of the panel structure of
>>> the data. Stata has very neat built-in procedures for dealing with
>>> such data.
>>>
>>> Very briefly, 2 pointers (I am ignoring the special wrinkle in your
>>> problem that you want to run 20 seoarate regressions for each "firm
>>> i-period t" pair- you would have to adapt the procedure accordingly):
>>>
>>> A. I would use -tsfill, full- to fill in the time values and balance the panel.
>>>
>>> B. If you use tsset panelvar datavar (or xtset), where panelvar is
>>> your panel identifier, and datevar the date variable, you can use:
>>>
>>> statsby _b _se, by(panelvar): regress y x
>>>
>>> to do all the regressions in one go (assuming a single regression for
>>> each "firm i-period t" pair), rather than separately within a long
>>> loop. You can collect the results saved in r-class macros, as with
>>> _b & _se above. See -help statsby-
>>>
>>> Having said all that, I have never tried to run a set of regressions
>>> with 30,000 firms & 200 time periods in a single run of a program!!!
>>> I suspect this will be painfully slow no matter how efficient your
>>> code. An obvious alternative would be to split the firms into, say, 10
>>> subsets, do the regression for each subset, and put all the results
>>> together.
>>>
>>> Hope this helps
>>>
>>> Partho Sarkar
>>> Consultant Econometrician
>>> Indicus Analytics
>>> New Delhi, India
>>>
>>>
>>> On Mon, Sep 19, 2011 at 5:22 AM, Stefano Rossi <[email protected]> wrote:
>>>> Dear Statalist Users,
>>>>
>>>> I wonder if you can help me make a faster loop?
>>>> I have an unbalanced panel of about 30,000 firms and 200 periods, and for each "firm i-period t" pair I need to run 10 regressions on the 12 observations from t-1 to t-12 of the same firm i, and another 10 regressions on the observations from t+1 to t+12 of the same firm i. I have come up with the following program, which works well as it does what it should do, but it is very slow (due to the many ifs I suspect) - here's a simplified version of it with just two regressions:
>>>>
>>>> forval z = 1/30000 {
>>>> levelsof period if firm==`z', local(sample)
>>>> foreach j of local sample {
>>>> local k = `j' - 13
>>>> capture reg y x if firm ==`z' & period<`j' & period>`k' & indicator==1
>>>> if _rc==0 {
>>>> predict y_hat, xb
>>>> replace before = y_hat[_n-1] if firm == `z' & period == `j'
>>>> drop y_hat
>>>> }
>>>> local w = `j' + 13
>>>> capture reg y x if firm ==`z' & period>`j' & period<`w' & indicator==1
>>>> if _rc==0 {
>>>> predict y_hat, xb
>>>> replace after = y_hat[_n+1] if firm == `z' & period == `j'
>>>> drop y_hat
>>>> }
>>>> }
>>>> }
>>>>
>>>> Right now, it takes several minutes for each firm, so if I run it for the whole sample it would take weeks.
>>>> Is there any way to make it (a lot) faster?
>>>>
>>>>
>>>> *
>>>> * 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/
>>>
>>
>
*
* 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/
```

**Follow-Ups**:**RE: st: how can i make my loop run faster?***From:*Stefano Rossi <[email protected]>

**References**:**st: how can i make my loop run faster?***From:*Stefano Rossi <[email protected]>

**Re: st: how can i make my loop run faster?***From:*Partho Sarkar <[email protected]>

**RE: st: how can i make my loop run faster?***From:*Stefano Rossi <[email protected]>

**Re: st: how can i make my loop run faster?***From:*Partho Sarkar <[email protected]>

**Re: st: how can i make my loop run faster?***From:*Partho Sarkar <[email protected]>

- Prev by Date:
**Re: st: Oddity with -bootstrap- handling an option on command input** - Next by Date:
**RE: st: how can i make my loop run faster?** - Previous by thread:
**Re: st: how can i make my loop run faster?** - Next by thread:
**RE: st: how can i make my loop run faster?** - Index(es):