funnel                 package:meta                 R Documentation

_P_l_o_t _t_o _a_s_s_e_s_s _f_u_n_n_e_l _p_l_o_t _a_s_y_m_m_e_t_r_y

_D_e_s_c_r_i_p_t_i_o_n:

     Draw a funnel or radial plot to assess funnel plot asymmetry in
     the active graphics window.

_U_s_a_g_e:

     funnel(x, y, xlim=NULL, ylim=NULL, xlab=NULL, ylab=NULL,
            comb.f=FALSE, axes=TRUE, labels=NULL, cex.lab=0.8,
            log="", yaxis="se", sm=NULL, ...)

     radial(x, y, xlim=NULL, ylim=NULL,
            xlab="Inverse of standard error",
            ylab="Standardised treatment effect (z-score)",
            comb.f=TRUE, axes=TRUE, labels=NULL, cex.lab=0.8,
            level=NULL, ...)

_A_r_g_u_m_e_n_t_s:

       x: An object of class 'meta', or estimated treatment effect in
          individual studies.

       y: Standard error of estimated treatment effect (mandatory if
          'x' not of class 'meta').

    xlim: The x limits (min,max) of the plot.

    ylim: The y limits (min,max) of the plot.

    xlab: A label for the x axis.

    ylab: A label for the y axis.

  comb.f: A logical indicating whether the pooled fixed effects
          estimate should be plotted.

    axes: A logical indicating whether axes should be drawn on the
          plot.

  labels: A character string specifying the text to be used as plotting
          symbol.

 cex.lab: The magnification to be used for x and y labels.

     log: A character string which contains '"x"' if the x axis is to
          be logarithmic, '"y"' if the y axis is to be logarithmic and
          '"xy"' or '"yx"' if both axes are to be logarithmic (applies
          only to function 'funnel').

   yaxis: A character string indicating which type of weights are to be
          used. Either '"se"', '"inv"', or '"size"' (applies only to
          function 'funnel'). 

      sm: A character string indicating underlying summary measure,
          e.g., '"RD"', '"RR"', '"OR"', '"WMD"', '"SMD"' (applies only
          to function 'funnel').

   level: The confidence level utilised in the plot (applies only to
          function 'radial').

     ...: Graphical parameters as in 'par' may also be passed as
          arguments.

_D_e_t_a_i_l_s:

     A funnel plot or radial plot, also called Galbraith plot, is drawn
     in the active graphics window. If 'comb.f' is TRUE, the pooled
     estimate of the fixed effects model is plotted. If 'level' is not
     NULL, the corresponding confidence limits are drawn.

     In the funnel plot, if 'yaxis' is '"se"', the standard error of
     the treatment estimates is plotted on the y axis which is likely
     to be the best choice (Sterne & Egger, 2001). Other possible
     choices for 'yaxis' are '"inv"' (inverse of the variance) and
     '"size"' (study size).

_A_u_t_h_o_r(_s):

     Guido Schwarzer sc@imbi.uni-freiburg.de

_R_e_f_e_r_e_n_c_e_s:

     Galbraith RF (1988a), Graphical display of estimates having
     differing standard errors. _Technometrics_, *30*, 271-281.

     Galbraith RF (1988b), A note on graphical presentation of
     estimated odds ratios from several clinical trials. _Statistics in
     Medicine_, *7*, 889-894.

     Light RJ & Pillemer DB (1984), _Summing Up. The Science of
     Reviewing Research_. Cambridge: Havard University Press.

     Sterne JAC & Egger M (2001), Funnel plots for detecting bias in
     meta-analysis: Guidelines on choice of axis. _Journal of Clinical
     Epidemiology_, *54*, 1046-1055.

_S_e_e _A_l_s_o:

     'metabias', 'metabin', 'metagen'

_E_x_a_m_p_l_e_s:

     data(Olkin95)
     meta1 <- metabin(event.e, n.e, event.c, n.c,
                      data=Olkin95, subset=c(41,47,51,59),
                      sm="RR", meth="I")

     ##
     ## Same results:
     ##
     oldpar <- par(mfrow=c(2,2))
     funnel(meta1)
     funnel(meta1$TE, meta1$seTE, sm="RR")
     par(oldpar)

     oldpar <- par(mfrow=c(2,2))
     funnel(meta1)
     funnel(meta1, yaxis="inv")
     funnel(meta1, yaxis="size")
     par(oldpar)

     funnel(meta1, comb.f=TRUE, xlim=c(0.1, 10), axes=FALSE)
     box()
     axis(1, at=c(0.1, 0.5, 1, 2, 10))
     axis(2)

     radial(meta1, level=0.95)

