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175 lines
6.4 KiB
Plaintext
175 lines
6.4 KiB
Plaintext
10 months ago
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help for ^metaninf^ version 1.0.2
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Influence of a single study in meta-analysis estimation
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-------------------------------------------------------
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^metaninf^ varlist [^if^ exp] [^in^ range] [, ^fixed fixedi random randomi^
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^rr or rd peto cornfield hedges cohen glass nosta^ndard
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^label(^label_vars^) il^evel^(^#^) ol^evel^(^#^) notable nograph^
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^sav^e^(^varname [^, replace^]^)^ ]
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Description
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-----------
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^metaninf^ investigates the influence of each individual study on the overall
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meta-analysis summary estimate. The command presents a table and a graph of
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the results of an influence analysis in which the meta-analysis is reestimated
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omitting each study in turn.
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The table numerically provides the results, with the rows of the table being
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the meta-analysis of all studies except the "omitted" study named in that row,
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and the usual, full meta-analysis (omitting none of the studies) being given
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as the "combined" results at the bottom of the table.
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The graph visually provides the same results in a plot, naming the omitted
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study on the left margin and presenting the resulting "omitted" meta-analytic
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summary statistics as a horizontal confidence interval. The full, "combined"
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results are shown as the solid vertical lines.
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No formal test of influence is given; rather, the program provides and displays
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results to which some general guidelines can be applied to assess influence.
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One such guideline is that an individual study is suspected of excessive
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influence if the point estimate of its "omitted" analysis lies outside the
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confidence interval of the "combined" analysis. Another quideline is that a
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study is excessively influential if its "omitted" meta-analytic estimate
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differs in significance relative to the "combined" analysis. Neither of these
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quidelines provides definitive proof that such a study should, or should not,
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be removed from the analysis; they merely provide a suggestion that some
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attention be paid to potential reasons for its influence.
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^metaninf^ uses program ^metan^ as its meta-analysis engine and its options are
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a direct subset of ^metan^'s. It is expected that users will merely edit a ^metan^
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command line by adding the "inf" suffix to the program name to run ^metaninf^.
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Like ^metan^, ^metaninf^ requires either four or six variables to be declared.
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When four variables are specified, analysis of binary data is performed.
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When six variables are specified, the data are assumed continuous.
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Binary data is presented as the 4 cell counts (a b c d) of a 2x2 table where
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a and b are the number of event & no-event subjects in the intervention group
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and c and d are similar numbers for the control group.
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. ^metaninf a b c d^
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Continuous data is presented as 6 values: the n, mean and sd for the treatment
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(or intervention) group followed by similar values for the control group.
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. ^metaninf nt mt sdt nc mc sdc^
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Options
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-------
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Scaling and pooling options
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---------------------------
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Options for binary data
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^rr^ pools risk ratios (the default).
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^or^ pools odds ratios.
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^rd^ pools risk differences.
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^fixed^ specifies a fixed effect model using the method of Mantel & Haenszel
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(the default).
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^fixedi^ specifies a fixed effect model using the inverse variance method.
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^peto^ specifies that Peto's assumption free method is used to pool odds
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ratios.
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^random^ specifies a random effects model using the method of DerSimonian &
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Laird, with the estimate of heterogeneity being taken from the
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Mantel-Haenszel model.
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^randomi^ specifies a random effects model using the method of DerSimonian &
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Laird, with the estimate of heterogeneity being taken from the inverse
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variance fixed effect model.
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^cornfield^ computes confidence intervals for odds ratios by the method of
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Cornfield, rather than the (default) Woolf method.
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Options for continuous data
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^cohen^ pools standardized mean differences by the method of Cohen
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(the default).
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^hedges^ pools standardized mean differences by the method of Hedges.
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^glass^ pools standardized mean differences by the method of Glass.
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^nostandard^ pools unstandardized mean differences.
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^fixed^ specifies a fixed effect model using the inverse variance method
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(the default).
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^random^ specifies a random effects model using the DerSimonian & Laird
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method.
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General output options
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----------------------
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^label(^[^namevar^=namevar] [^, yearvar^=yearvar]^)^
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labels the data by its name, year or both. However, neither option
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is required. For the table display the overall length of the label is
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restricted to 16 characters.
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^ilevel()^ specifies the significance level (eg 90,95,99) for the
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individual trial confidence intervals.
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^olevel()^ specifies the significance level (eg 90,95,99) for the
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overall (pooled) confidence intervals.
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^ilevel^ and ^olevel^ need not be the same, and by default are equal
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to the significance level specified using the ^set level^ command.
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^notable^ prevents display of the table of results.
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^nograph^ prevents display of the graph.
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^save(^varname [^, replace^]^)^ saves the jackknifed estimates.
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Note
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----
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To run ^metaninf^, the ^metan^ command [STB-44: sbe24] must be installed.
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Acknowledgements
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----------------
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^metaninf^ is a direct rip-off of ^metainf^ (by Aurelio Tobias; see STB-47: sbe26;
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STB-56: sbe26.1). It blatently uses ^metan^ (by Michael J Bradburn, Jonathan J
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Deeks and Douglas G Altman; see STB-44: sbe24) as its meta-analysis calculation
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engine and ^mhplot^, a slight variation of ^hplot^ (by Nicolas Cox), as its
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graphic engine. The current author is indebted to the above authors for all
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their hard work, thus allowing this program to be written with no apparent
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personal intellectual input. Thanks guys!
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Examples
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--------
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. ^metaninf a b c d, fixedi or label(namevar=studyid, yearvar=year)^
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. ^metaninf nt mt sdt nc mc sdc, cohen notable^
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Author
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------
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Thomas J Steichen, steichen@triad.rr.com
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Also see
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--------
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On-line: help for @metan@, and if installed: @metainf@, @meta@, @metareg@, @metacum@,
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@metabias@, @metatrim@, @metap@, @galbr@, @funnel@, @labbe@, and @hplot@.
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