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Re: st: RE: RE: xtivreg2 -- Instruments dropped


From   Ivan Png <[email protected]>
To   [email protected]
Subject   Re: st: RE: RE: xtivreg2 -- Instruments dropped
Date   Sun, 16 Jan 2011 11:25:26 +0800

Sorry, Mark.  I've updated the data-set.

On Sat, Jan 15, 2011 at 10:29 PM, Schaffer, Mark E
<[email protected]> wrote:
> Ivan,
>
> I had the same problem as Eric.  And there must be something else wrong, since there's only one instrument listed (L.govr_r) and you refer to "instruments".
>

IP: I meant instruments -- in the sense that I used different
instruments in various specifications, and each one was dropped.

> Did xtivreg2 report collinearities among your instruments as a reason for dropping some?  Did xtivreg?  If so, were the dropped variables the same?

IP; Neither reported collinearities.

> You might also want to compare the first-stage regressions of xtivreg2 and xtivreg.
>
> Oh, and tell us which versions of xtivreg2, xtivreg and Stata you are using.

IP: Stata/IC 10.1.  Sorry, please advise how to identify version of
xtivreg2 and xtivreg


> --Mark
>
>> -----Original Message-----
>> From: [email protected]
>> [mailto:[email protected]] On Behalf Of DE
>> SOUZA Eric
>> Sent: 15 January 2011 12:02
>> To: [email protected]
>> Subject: st: RE: xtivreg2 -- Instruments dropped
>>
>> Check the instruction you have posted:
>> govr_r does not exist
>>
>>
>>
>> Eric de Souza
>> College of Europe
>> Brugge (Bruges), Belgium
>> http://www.coleurope.eu
>>
>>
>> -----Original Message-----
>> From: [email protected]
>> [mailto:[email protected]] On Behalf Of Ivan Png
>> Sent: 15 January 2011 12:43
>> To: [email protected]
>> Subject: st: xtivreg2 -- Instruments dropped
>>
>> Dear Stata-list:
>>
>> I'm having difficulty with xtivreg2
>>
>> Each time, the system drops the instruments for the variable L.utsa.
>> utsa is a state-time variable that varies across states and
>> times. I checked the instruments: they are state- and
>> time-varying.   I don't understand why the system drops the
>> instruments.  (I tried xtivreg and it works, but I would like
>> to use xtivreg2 so that I can get cluster standard errors and
>> the diagnostics for weak instruments).
>>
>>
>> Please help.  Many thanks!
>>
>> Data-set:
>> http://www.comp.nus.edu.sg/~ipng/research/company_wrkg.dta
>>
>>
>> Code:
>> . xtset gvkey year
>>
>> . xi: xtivreg2 xrdr_ln revtr_ln mktbook_mm ebitdar_ln taxcred ///
>>     (L.utsa = L.govr_r) i.year trend_AL - trend_WY ///
>>     if xrdr_count >= 6  , fe cluster(state_sic)
>>
>>
>>
>>
>> --
>> Ivan Png
>> National U of Singapore
>>
>>
>>
>>
>> --
>> Skype: ipng00
>> T: +65 6516 6807
>>
>>
>>
>> --
>> Skype: ipng00
>> T: +65 6516 6807
>>
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>
>
> --
> Heriot-Watt University is a Scottish charity
> registered under charity number SC000278.
>
>
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