`addpoly.Rd`

Function to add polygons (sometimes called ‘diamonds’) to a forest plot, for example to show summary estimates for subgroups of studies or to show fitted/predicted values based on models involving moderators.

`addpoly(x, ...)`

- x
either an object of class

`"rma"`

, an object of class`"predict.rma"`

, or the values at which polygons should be drawn. See ‘Details’.- ...
other arguments.

Currently, methods exist for three types of situations.

In the first case, object `x`

is a fitted model coming from the `rma.uni`

, `rma.mh`

, `rma.peto`

, `rma.glmm`

, or `rma.mv`

functions. The model must either be an equal- or a random-effects model, that is, the model should not contain any moderators. The corresponding method is `addpoly.rma`

. It can be used to add a polygon to an existing forest plot (usually at the bottom), showing the summary estimate (with its confidence interval) based on the fitted model.

Alternatively, `x`

can be an object of class `"predict.rma"`

obtained with the `predict`

function. In this case, polygons based on the predicted values are drawn. The corresponding method is `addpoly.predict.rma`

.

Alternatively, object `x`

can be a vector with values at which one or more polygons should be drawn. The corresponding method is `addpoly.default`

.

Viechtbauer, W. (2010). Conducting meta-analyses in R with the metafor package. *Journal of Statistical Software*, **36**(3), 1–48. https://doi.org/10.18637/jss.v036.i03

`addpoly.rma`

, `addpoly.predict.rma`

, and `addpoly.default`

for the specific method functions.

`forest`

for functions to draw forest plots to which polygons can be added.