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Re: st: Problem with -metareg-
Dear Tiago,
Hard to tell what the cause of the convergence problem is as clearly i
can't replicate it without the original dataset. The different
behaviour when you re-input the data may be more likely to be due to
the tiny differences between the original stored values and the result
of re-inputting them to 6 or 7 significant figures than the presence
or abscence of additional variables. If you want to email me the
original dataset (to [email protected]) i'll investigate
further. Switching to the -mm- option (method-of-moments estimate of
between study variance) instead of the -reml- option (residual maximum
likelihood) should avoid the numerical problems and give the same
answer in this instance where the estimated between-study variance is
zero.
--
Roger Harbord
http://www.epi.bris.ac.uk/staff/rharbord.htm
On Tue, Feb 10, 2009 at 6:41 PM, Tiago V. Pereira
<[email protected]> wrote:
> Dear Statalisters,
>
> Using my whole dataset (with several others variables) I type:
>
> . metareg logor, wsse(selogor) reml
>
> and obtain:
>
> numerical derivatives are approximate
> nearby values are missing
> numerical derivatives are approximate
> nearby values are missing
> numerical derivatives are approximate
> nearby values are missing
> could not calculate numerical derivatives
> missing values encountered
> r(430);
>
> Then, I do the following: clear, inpute the same data but only the two
> variables and obtain sucessfully the result I am looking for:
>
> clear
>
>
> */---------START-------------
> input logor selogor
> .0800427 .8641729
> .2786815 .1604731
> -1.400893 1.19818
> .537752 .5122404
> end
> metareg logor, wsse(selogor) reml
> */--------END--------------------
>
> Meta-regression Number of obs =
> 4
> REML estimate of between-study variance tau2 =
> 0
> % residual variation due to heterogeneity I-squared_res =
> 0.00%
> With Knapp-Hartung modification
> ------------------------------------------------------------------------------
> logor | Coef. Std. Err. t P>|t| [95% Conf.
> Interval]
> -------------+----------------------------------------------------------------
> _cons | .268642 .1496053 1.80 0.170 -.207469
> .7447529
> ------------------------------------------------------------------------------
>
> Does anyone have a guess about what is going on with -metareg- (the most
> recent version)?
>
>
> Cheers!
>
> Tiago
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