{smcl} {* Mar 21 2010}{...} {hline} help for {hi:allsubsets} {hline} {title:All subsets (combinatorial) meta-analysis} {p 4 17 2} {cmdab: allsubsets} varlist [{hi:if} expression] [{hi:in} range], {hi:s}ave({it:filename}) [{hi:maxstudies}({it:integer}) {hi:replace} ] {title:Description} {p 4 8 2} {cmd:allsubsets} performs 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={hi:maxstudies} studies. See Options. {title:Suggested citation:} {p 4 8 2} Olkin I, Dahabreh IJ, Trikalinos TA. {browse "http://onlinelibrary.wiley.com/doi/10.1002/jrsm.1053/abstract":GOSH - A graphical display of study heterogeneity}. {it:Research Synthesis Methods}. 2012;3(3):214-223. See also the {browse "http://www.cebm.brown.edu/resources":Center for Evidence-based Medicine (CEBM)} at Brown University for updates or additional materials. {hline} {p 4 8 2} {hi:varlist} Expects two numeric variables: the effect size {it:Theta} and its variance {it:var_theta}. {hline} {p 4 8 2} In the saved file one finds the following variables: {p 4 8 2} {it:study_ES}: the effect size of the study. has non-missing values only for N (# of studies) observations. {p 4 8 2} {it:study_var}: the variance of each study. has non-missing values only for N (# of studies) observations. {p 4 8 2} {it:es_fem}: fixed effects meta-analysis result {p 4 8 2} {it:es_rem}: random effects meta-analysis result {p 4 8 2} {it:df}: degrees of freedom {p 4 8 2} {it:I2}: I^2 value {p 4 8 2} {it: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. {p 4 8 2} {it:pRem_z}: p-value for the overall effect with the random effects model {p 4 8 2} {it:var_fem}: variance of the summary fixed effects estimate {p 4 8 2} {it:var_rem}: variance of the summary random effects estimate {p 4 8 2} {it:Q}: Cochran's Q {p 4 8 2} {it:tau2}: DerSimonian and Laird 1-step tau^2 {p 4 8 2} {it:pFem_z}: p-value for the overall effect with fixed effects {hline} {p 4 8 2} Options for {hi:allsubsets} {p 4 8 2} {hi:save} Give the nane of the file where the command will save results {p 4 8 2} {hi:replace} Whether or not to replace the file if it exists. {p 4 8 2} {hi:maxstudies} The 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.