st: update of -metareg- available on SSC

[Roger Harbord <roger.harbord@bristol.ac.uk>]

An update of the -metareg- package for Stata is available for download from 
the SSC archive, thanks to archive maintainer Kit Baum. To describe and 
install the package, type -ssc describe metareg- from Web-aware Stata. 
Previous users of -metareg- should type -ssc install metareg, replace- .

The main changes to the previous version are:

(1) The package now includes a dialog box written by Tom Steichen. This is 
most simply accessed by clicking the link at the top of the help-file or 
typing -db metareg- after installation.

(2) The default is now to use the modification to the variance of the 
estimated coefficients suggested by Knapp & Hartung (2003), accompanied by 
the use of a t-distribution when calculating p-values and confidence 
intervals (unless option permute() is specified.) This is more conservative 
than the conventional variance estimate and z-test, which can still be 
obtained by specifying the -z- option.

(3) The command should now work in Stata 7 (although the dialog box requires 
Stata 8, clearly). However I haven't had an opportunity to test it using 
Stata 7 so would welcome feedback from Stata 7 users.


For further information on the methods implemented in -metareg- ,including 
permutation tests and a summary and evaluation of (2), see:
Higgins JPT, Thompson SG (2004).  Controlling the risk of spurious findings
from meta-regression.  Statistics in Medicine 23:1663-1682.
http://www3.interscience.wiley.com/cgi-bin/abstract/108565626/ABSTRACT

For full details of (2) see:
Knapp G, Hartung J. 2003.  Improved tests for a random effects 
meta-regression with a single covariate.  Statistics in Medicine 22: 
2693-2710.
http://www3.interscience.wiley.com/cgi-bin/abstract/104554585/ABSTRACT


My thanks to Tom Steichen for completely rewriting his previous -metareg- 
dialog box, Nick Cox for writing -matvsort- which is called by -metareg- (and 
is installed automatically along with -metareg- if not previously installed) 
and once again to Stephen Sharp for giving his permission to revise his 
original -metareg- program (version 1.06 published January 1998 in STB-42 as 
package sbe23) and to issue the new version under the same name.

Roger.
----------------------------------------------------
Roger Harbord     mailto:roger.harbord@bristol.ac.uk
Department of Social Medicine, University of Bristol


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