how the sort the rows by mean difference.
Options are to sort using the mean difference from
matching, stratificaiton, both individually, or no
sorting.
ci.sig.color
the color used for confidence
intervals that do not span zero.
plot.overall
whether to plot vertical lines for
the overall (non-bootsrapped) estimate and confidence
interval.
plot.bootstrap
whether to plot vertical lines for
the bootstrap pooled estimate and confidence interval.