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Re: st: Meta-analysis questions


From   "Tiago V. Pereira" <tiago.pereira@mbe.bio.br>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Meta-analysis questions
Date   Fri, 24 Sep 2010 03:20:28 -0300 (BRT)

I just would like to mention that I have done some confusion with the begg
option in -metabias-.

As the help file shows " graph - graph displays a Galbraith plot (the
standard normal deviate of intervention effect estimate against its
precision) for the original
        Egger test or a modified Galbraith plot of Z/sqrt(V) versus sqrt(V)
        for Harbord's modified test. ****There is no corresponding plot
for the
        Peters or Begg tests.*****

The message you got has nothing to do with the type of data you are
dealing with.













In practice, as long as the studies to be combined are not very small, I
believe that both random and randomi approaches will give virtually
identical results.

 If you are using data based on logor/selogor, I guess -metan- uses
automatically randomi (or fixedi) even if you specify fixed/random.

Cheers!

Tiago



> Dear Rui,
>
> 1) Yes, the default is the fixed-effect inverse variance method if your
data is based on logor and selogor; typing "metan logor selogor,
randomi" will give you the DerSimonian-Laird method.
>
> Type
>
> help metan
>
> to see the options.
>
>
> 2) As the message says, the option begg can handle only raw data (e.g.
2x2 tables, with a b c d counts)
>
> Type
>
> help metabias
>
> for further information
>
>
> 3) You need to provide more information on your data set, and how the
typename variable was coded.
>
> Also, try the pdfs that the following link shows :
>
> http://tinyurl.com/342osna
>
>
> Hope this helps.
>
> Tiago
>
>
> --------------
>
> Hi. I'm a new user of STATA and the meta-analysis commands and have a
couple of questions...
>
> 1) For "metan logor selogor" command, is the default fixed effect? and
if I would like to test for the DerSimonian & Laird random effects is it
correct to type "metan logor selogor, random"?
>
> 2) I'm trying to do the command "metabias logor selogor, graph (begg)"
but is giving me the following error message:
> Note: data input format theta se_theta assumed.
> Only Egger or Begg tests can be used with two input variables theta
se_theta
> r(198);
>
> What is causing this and how should I resolve it?
>
> 3) I'm trying to do the command "metafunnel logor selogor, by
> (typename)" where typename is the type of different study designs but is
it giving me the following error message:
> Note: default data input format (theta, se_theta) assumed.
> type mismatch
> r(109);
>
> If i don't put in "by (typename)" it works fine and giving me the funnel
plot. What is causing this and how should I resolve it?
>
> Thank you so much in advance for your guidance.
>
> Rui
>
>




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