which meta-analysis model should be used to show (shrinked)
estimates of the study effect sizes. The name must match the corresponding
name in the list meta. Can be suppressed by shrinked = ""
summary
character vector with two values: first, either "mean"
or "50%"; and second, either highest-probability-density interval "hpd"
or the Bayesian credibility interval "bci".
mar
margin of the plot in the order c(bottom, left, top, right)
(see par)
cex.axis
size of the y-axis annotation for the labels of studies.