----------------------------------------------------------------------------------------------------
help confunnel                                                                       (SJ8-2: gr0033)
----------------------------------------------------------------------------------------------------



Title



    confunnel -- Contour-enhanced funnel plots for meta-analysis






Syntax



        confunnel varname1 varname2 [if] [in] [, options]






    options                             Description
    ----------------------------------------------------------------------------------------------
    contours(numlist)                    specify significance levels of the contours to be
                                          plotted; default is 1%, 5%, and 10% significance levels
    contcolor(colorstyle)                specify color of the contour lines if shadedcontours is
                                          not specified
    extraplot(plots)                     specify additional plots to overlay the funnel plot
    functionlowopts(options)             pass options to the twoway function commands used to draw
                                          the contours
    functionuppopts(options)             pass options to the twoway function commands used to draw
                                          the contours
    legendlabels(labels)                 specify labels in the legend for added items
    legendopts(options)                  specify options that affect the plot legend
    metric(se|invse|var|invvar)          the scale of the y axis; either se, invse, var, or invvar
    onesided(lower|upper)                lower- or upper-tailed, one-sided significance contours
    scatteropts(options)                 specifies any of the options documented in scatter
    shadedcontours                       specify shaded, instead of black, contour lines
    [no]shadedregions                    specify or suppress shaded regions between the contours
    solidcontours                        specify solid, instead of dashed, contour lines
    studylab(string)                     the legend label for the scatter points
    twowayopts(twoway_options)           pass options to the twoway plot
    twoway_options                       pass options to the twoway plot
    ----------------------------------------------------------------------------------------------






Description



    confunnel plots contour-enhanced funnel plots for assessing small-study reporting bias in
    meta-analysis.



    Contours illustrating the statistical significance of the study-effect estimates are plotted
    from either a one- or two-tailed test.



    confunnel requires two input variables; varname1 a variable of effect estimates such as log
    odds ratios and varname2 a variable of the standard errors of the effect estimates.



    The y axis can be specified using different scales, namely, standard error, inverse standard
    error, variance, and inverse variance.






Options



    contours(numlist) specifies the significance levels of the contours to be plotted; the default
        is contours(1 5 10). There are only distinct line patterns for 8 significance levels. See 
        numlist.



    contcolor(colorstyle) specifies the color of the contour lines if noshadedcontours is
        specified. See [G] colorstyle.



    extraplot(plots) specifies one or multiple additional plots to be overlaid on the funnel plot.



    functionlowopts(options) and functionuppopts(options) pass options to the twoway function
        commands used to draw the significance contours; for example, the line widths can be
        changed. See [G] graph twoway function.



    legendlabels(labels) specifies labels in the legend for extra elements added to the funnel
        plot.  The option will take the form:  legendlabels(`"8 "new label""').



    legendopts(options) passes options to the plot legend. See [G] legend_option.



    metric(se|invse|var|invvar) specifies the metric of the y axis of the plot.  se, invse, var,
        and invvar stand for standard error, inverse standard error, variance, and inverse
        variance, respectively; the default is se.



    onesided(lower|upper) can be lower or upper, for lower-tailed or upper-tailed levels of
        statistical significance, respectively.  If unspecified, two-sided significance levels are
        used to plot the contours.



    scatteropts(options) specifies any of the options documented in [G] graph twoway scatter.



    shadedcontours specifies shaded contour lines; specify with the noshadedregions option.



    [no]shadedregions specifies or suppresses shaded regions between the contours.  This option
        provides plots that are more similar to those in the original paper by Peters et al.
        (2008) and the Cochrane Handbook.  A plot with shadedregions is now the default.



    solidcontours specifies solid contour lines; specify with the shadedcontours and
        noshadedregions option.



    studylab(string) specifies the label for the scatter points in the legend.  If not specified
        the default is "Studies".



    twowayopts(options) specifies options passed to the twoway plotting function; see [G]
        twoway_options.



    twoway_options see [G] twoway_options. As of confunnel version 1.0.5 twoway options can be
        specified at the end of the options and do not have to be within twowayopts.



Remarks



    The confunnel command is based on an idea by Peters et al. (2008) to superimpose contours of
    statistical significance on a funnel plot in a meta-analysis. The command was explained in
    Palmer et al. (2008). Superimposing contours on funnel plots has also been suggested by
    Spiegelhalter (2005) in a slightly different context.



    confunnel can be used in conjunction with the results of the metan, metatrim, and metabias
    commands.  See meta in Stata version 10 for information about user-written commands for
    meta-analysis.






Examples



    The following examples use the example dataset accompanying metan.



    . confunnel logOR selogOR
    (click to run)



    . confunnel logOR selogOR, noshadedregions
    (click to run)



    . confunnel logOR selogOR, solidcontours shadedcontours noshadedregions
    (click to run)



    . confunnel logOR selogOR, metric(invse)
    (click to run)



    . confunnel logOR selogOR, onesided(upper) noshadedregions
    (click to run)






References



    Palmer, T. M., J. L. Peters, A. J. Sutton, and S. G. Moreno. 2008.  Contour enhanced funnel
        plots for meta-analysis. Stata Journal 8: 242-254.



    Peters, J. L., A. J. Sutton, D. R. Jones, K. R. Abrams, and L. Rushton.  2008.
        Contour-enhanced meta-analysis funnel plots help distinguish publication bias from other
        causes of asymmetry. Journal of Clinical Epidemiology. 61: 991-996.



    Spiegelhalter, D. J. 2005. Funnel plots for comparing institutional performance.  Statistics
        in Medicine 24: 1185-1202.



    Sterne, J. A. C., and M. Egger. 2001. Funnel plots for detecting bias in meta-analysis:
        Guidelines on choice of axis.  Journal of Clinical Epidemiology 54: 1046-1055.



    Sterne, J. A. C., and R. M. Harbord. 2004. Funnel plots in meta-analysis. Stata Journal 4:
        127-141.



    Sterne, J. A. C., M. Egger, and D. Moher. 2008. Chapter 10: Addressing reporting biases;
        Cochrane Handbook for Systematic Reviews of Interventions Version 5.0.1.






Author



    Tom Palmer, MRC Integrative Epidemiology Unit and Population Health Sciences, University of
        Bristol, UK.  tom.palmer@bristol.ac.uk.
 
    Jaime Peters wrote the first version of this command.



    Thanks to Santiago G. Moreno for testing the command.



    Please report any errors you may find.






Also see



    Article: Stata Journal, volume 8, number 2: gr0033



    Online:  metabias, metafunnel, metan (if installed)