Create pooled summary diamond shape

Usage

make_summary(est, lower, upper, sizes = 1, gp, xlim, nudge_y = 0)

est: Point estimation. Can be a list for multiple columns and/or multiple groups. If the length of the list is larger than then length of ci_column, then the values reused for each column and considered as different groups.
lower: Lower bound of the confidence interval, same as est.
upper: Upper bound of the confidence interval, same as est.
sizes: Size of the point estimation box, can be a vector or a list. The value is a multiple of one line of text, so 1 draws a point as tall as the base_size of the theme. The same scale applies to the summary diamond. Values are used as they are, unless scale_sizes is used to read them as study weights; useful values are roughly between 0.2 and 1.5, and a warning is given when the plot is drawn if they are outside 0.1 to 2.
gp: Graphical parameters of gpar. Please refer to forest_theme for more details.
xlim: Limits for the x-axis as a vector of length 2, i.e. c(low, high). By default the minimum and maximum of the lower and upper values are used.
nudge_y: Vertical adjustment to nudge groups by, must be within 0 to 1. Defaults to 0; for grouped forest plots a value of 0 is bumped to 0.1 automatically so that group CIs do not overplot. Set explicitly to override.

A gTree object