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All subsets (combinatorial) meta-analysis

allsubsetsvarlist [ifexpression] [inrange],save(filename) [maxstudies(integer)replace]

Description

allsubsetsperforms all subsets (combinatorial) meta-analysis in a set of studies and saves results. By default the routine performs fixed effects meta-analysis using the inverse variance method, and random effects meta-analysis using the DerSimonian and Laird random effects model.Let N be the number of studies in the meta-analysis. Then the number of possible subsets is -1+2^N. The command handles up to N=

maxstudiesstudies. See Options.

Suggested citation:Olkin I, Dahabreh IJ, Trikalinos TA. GOSH - A graphical display of study heterogeneity.

Research Synthesis Methods. 2012;3(3):214-223.See also the Center for Evidence-based Medicine (CEBM) at Brown University for > updates or additional materials.

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varlistExpects two numeric variables: the effect sizeThetaand its variancevar_theta.-------------------------------------------------------------------------------

In the saved file one finds the following variables:

study_ES: the effect size of the study. has non-missing values only for N (# of studies) observations.

study_var: the variance of each study. has non-missing values only for N (# of studies) observations.

es_fem: fixed effects meta-analysis result

es_rem: random effects meta-analysis result

df: degrees of freedom

I2: I^2 value

subset: codes which studies are in the subset. Studies are named with lowercase letters (e.g. "a", "b"). "a b g" means that the 2nd, 3rd and 7th study are included in the subset.

pRem_z: p-value for the overall effect with the random effects model

var_fem: variance of the summary fixed effects estimate

var_rem: variance of the summary random effects estimate

Q: Cochran's Q

tau2: DerSimonian and Laird 1-step tau^2

pFem_z: p-value for the overall effect with fixed effects

------------------------------------------------------------------------------- Options for

allsubsets

saveGive the nane of the file where the command will save results

replaceWhether or not to replace the file if it exists.

maxstudiesThe maximum number of studies that are allowed. This depends on your computer's RAM. The default is N=20 (1'048'575 subsets). Specifying too high an N results in a memory allocation error.