Add Polygons to Forest Plots (Default Method)
Function to add one or more polygons to a forest plot.
## Default S3 method:
addpoly(x, vi, sei, ci.lb, ci.ub, cr.lb, cr.ub,
rows=-1, level=95, annotate=TRUE, digits=2, width, mlab,
transf, atransf, targs, efac=1, col, border, fonts, cex, ...)x |
vector with the values at which the polygons should be drawn. |
vi |
vector with the corresponding variances. |
sei |
vector with the corresponding standard errors note: only one of the two, |
ci.lb |
vector with the corresponding lower confidence interval bounds. Not needed if |
ci.ub |
vector with the corresponding upper confidence interval bounds. Not needed if |
cr.lb |
optional vector with the corresponding lower credibility/prediction interval bounds. |
cr.ub |
optional vector with the corresponding upper credibility/prediction interval bounds. |
rows |
vector specifying the rows (or more generally, the horizontal positions) for plotting the polygons (defaults is |
level |
numerical value between 0 and 100 specifying the confidence interval level (the default is 95). |
annotate |
logical specifying whether annotations should be added to the plot for the polygons that are drawn (the default is |
digits |
integer specifying the number of decimal places to which the annotations should be rounded (the default is 2). |
width |
optional integer to manually adjust the width of the columns for the annotations. |
mlab |
optional character vector with the same length as |
transf |
optional argument specifying the name of a function that should be used to transform the |
atransf |
optional argument specifying the name of a function that should be used to transform the annotations (e.g., |
targs |
optional arguments needed by the function specified via |
efac |
vertical expansion factor for the polygons. The default value of 1 should usually work okay. |
col |
optional character string specifying the name of a color to use for the polygons. If unspecified, the function sets a default color. |
border |
optional character string specifying the name of a color to use for the border of the polygons. If unspecified, the function sets a default color. |
fonts |
optional character string specifying the font to use for the labels and annotations. If unspecified, the default font is used. |
cex |
optional symbol expansion factor. If unspecified, the function tries to set this to a sensible value. |
... |
other arguments. |
The function can be used to add one or more polygons to an existing forest plot created with the forest function. For example, summary estimates based on a model involving moderators can be added to the plot this way. See example below.
To use the function, one should specify the values at which the polygons should be drawn (via the x argument) together with the corresponding variances (via the vi argument) or with the corresponding standard errors (via the sei argument). Alternatively, one can specify the values at which the polygons should be drawn together with the corresponding confidence interval bounds (via the ci.lb and ci.ub arguments). Optionally, one can also specify the bounds of the corresponding credibility/prediction interval bounds via the cr.lb and cr.ub arguments.
The arguments transf, atransf, efac, and cex should always be set equal to the same values used to create the forest plot.
Wolfgang Viechtbauer wvb@metafor-project.org http://www.metafor-project.org/
Viechtbauer, W. (2010). Conducting meta-analyses in R with the metafor package. Journal of Statistical Software, 36(3), 1–48. https://www.jstatsoft.org/v036/i03.
### meta-analysis of the log risk ratios using a mixed-
### effects model with absolute latitude as a moderator
res <- rma(measure="RR", ai=tpos, bi=tneg, ci=cpos, di=cneg, mods = ~ ablat,
slab=paste(author, year, sep=", "), data=dat.bcg)
### forest plot of the observed risk ratios
forest(res, addfit=FALSE, atransf=exp, xlim=c(-8,5), ylim=c(-4.5,16), cex=.8,
order=order(dat.bcg$ablat), ilab=dat.bcg$ablat, ilab.xpos=-4,
header="Author(s) and Year")
### predicted average log risk ratios for 10, 30, and 50 degrees absolute latitude
x <- predict(res, newmods=c(10, 30, 50))
### add predicted average risk ratios to forest plot
addpoly(x$pred, sei=x$se, atransf=exp, col="white", rows=-2,
mlab=c("- at 10 Degrees", "- at 30 Degrees", "- at 50 Degrees"), cex=.8)
abline(h=0)
text(-8, -1, "Model-Based Estimates of RR:", pos=4, cex=.8)
text(-4, 15, "Latitude", cex=.8, font=2)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.