funnelplot: Funnel plot for publication bias

Description

Plots the treatment difference for trials against the size of the trial (or other specified variable). Asymmetry in the plot often indicates publication bias. Generic, with methods for meta-analysis objects.

Usage

funnelplot(x,…)
# S3 method for default
funnelplot(x, se, size=1/se, summ=NULL,
        xlab="Effect", ylab="Size", colors=meta.colors(),
        conf.level=0.95, plot.conf=FALSE,
        zero=NULL, mirror=FALSE, …)

Arguments

Treatment difference

Standard error of x

size

Variable for the vertical axis

summ

summary treatment difference

xlab

x-axis label

ylab

y-axis label

colors

list of colors for components of the plot

conf.level

For confidence interval plotting

plot.conf

Plot confidence intervals instead of just points?

zero

location of a null hypothesis line

mirror

Add points reflected around summ?

…

further arguments to be passed from or to methods.

Value

Used for its side-effect.

Details

With the default value of size the plot should appear as a upwards-pointing funnel shape. Publication bias often causes one side of the funnel to be trimmed near the base. The mirror plot creates a symmetric funnel by reflecting the plot around the summ value. In the presence of publication bias the added points will separate from the real studies.

Examples

Run this code

# NOT RUN {
data(catheter)
a <- meta.MH(n.trt, n.ctrl, col.trt, col.ctrl, data=catheter,
             names=Name, subset=c(13,6,5,3,7,12,4,11,1,8,10,2))
funnelplot(a$logOR, a$selogOR)
funnelplot(a$logOR, a$selogOR,
           plot.conf=TRUE, summ=a$logMH, mirror=TRUE)
funnelplot(a, plot.conf=TRUE)
# }

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