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RE: st: RE: ivreg2 warning, even after "partialling out"


From   "Schaffer, Mark E" <[email protected]>
To   "[email protected]" <[email protected]>
Subject   RE: st: RE: ivreg2 warning, even after "partialling out"
Date   Thu, 14 Nov 2013 16:41:48 +0000

Jin,

It sounds like you have too many explicit regressors for cluster, and maybe too many in general - if you have many hundreds of explicit regressors,  Stata will have to invert a very large matrix, and that is inviting numerical accuracy problems.

A few thoughts:

Try partialling out $exogctrl AND _I* in the same regression, i.e., partial($exogctrl _I*).  This is what I originally had in mind.

How many variables are in $exogctrl?  How many are in _I*?

What is matsize set to?  You can find out with

	query memory

in Stata.

--Mark

> -----Original Message-----
> From: [email protected] [mailto:owner-
> [email protected]] On Behalf Of Jin-Hyun Bae
> Sent: 14 November 2013 14:19
> To: [email protected]
> Subject: Re: st: RE: ivreg2 warning, even after "partialling out"
> 
> Hello Mark,
> 
> Thank you for your suggestion. I tried to partial out the full list of
> controls and also a subset excluding binary controls, but I get the
> following error.
> 
> ivreg2 selfemp1 cultdist $exogctrl _I*, cluster (nat cisstate) partial(_I*)
> matsize too small
> r(908);
> 
> Also, since you mentioned that it would be difficult to see where the
> problem lies without seeing the results, I would like to respond to
> that. Unfortunately, the data restrictions I have prevent me from
> sending out the raw results. Could you tell me what you would like to
> know, or what I should be looking out for?
> 
> Thank you again,
> Jin
> 
> Date: Thu, 14 Nov 2013 00:23:42 +0000
> From: "Schaffer, Mark E" <[email protected]>
> Subject: st: RE: ivreg2 warning, even after "partialling out"
> 
> Jin,
> 
> > -----Original Message-----
> > From: [email protected] [mailto:owner-
> > [email protected]] On Behalf Of Jin-Hyun Bae
> > Sent: 13 November 2013 23:20
> > To: [email protected]
> > Subject: st: ivreg2 warning, even after "partialling out"
> >
> > Hello!
> >
> > I'm having problems nailing down the cause of a warning message when
> using
> > ivreg2. I am running OLS with two-way clustering (nat, cisstate) and have
> added
> > dummies for these variables.
> >
> > selfemp1 is a binary variable.
> > cultdist is a continuous variable.
> > _I* is a list of dummies based on nat and cisstate. I created these based on
> the
> > example code in the ivreg2 help file.
> >
> > When I run
> > ivreg2 selfemp1 cultdist _I*, cluster (nat cisstate) partial(_I*) I don't get a
> > warning.
> >
> > But when I add a list of exogenous controls ($exogctrl), I get the following
> > "Warning: estimated covariance matrix of moment conditions not of full
> rank.
> > model tests should be interpreted with caution."
> >
> > This is the exact code I used.
> > ivreg2 selfemp1 cultdist $exogctrl _I*, cluster (nat cisstate) partial(_I*)
> >
> > Also, if it helps, I get the same message when using the following code.
> > ivreg2 selfemp1 cultdist $exogctrl, cluster (nat cisstate)
> >
> > In all cases I have 77 clusters for nat and 42 clusters for cisstate, and there
> are
> > no missing F values or std errors.
> >
> > I updated ivreg2 beforehand so it is up to date.
> >
> > Jin
> 
> It's hard to tell for sure without seeing the output, but most likely
> you are running into the not-full-rank-because-of-not-enough-clusters
> issue.
> 
> Does the error message go away if you also partial out the additional
> exogenous controls in $exogctrl?
> 
> - --Mark
> 
> > *
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> 
> 
> - -----
> Sunday Times Scottish University of the Year 2011-2013
> Top in the UK for student experience
> Fourth university in the UK and top in Scotland (National Student Survey
> 2012)
> 
> We invite research leaders and ambitious early career researchers to
> join us in leading and driving research in key inter-disciplinary themes.
> Please see www.hw.ac.uk/researchleaders for further information and how
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> 
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> registered under charity number SC000278.
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
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> *   http://www.ats.ucla.edu/stat/stata/


----- 
Sunday Times Scottish University of the Year 2011-2013
Top in the UK for student experience
Fourth university in the UK and top in Scotland (National Student Survey 2012)


We invite research leaders and ambitious early career researchers to 
join us in leading and driving research in key inter-disciplinary themes. 
Please see www.hw.ac.uk/researchleaders for further information and how
to apply.

Heriot-Watt University is a Scottish charity
registered under charity number SC000278.


*
*   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/


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