Added an optional parametric confidence ribbon in ggsmatr() through the new arguments ci, ci.alpha and n.
The ribbon uses the slope confidence intervals already stored in the sma() fit (Slope_lowCI and Slope_highCI) and is pivoted at each group centroid. Given that SMA lines pass through the group mean, this envelope presents the uncertainty of the slope rather than an OLS geom_smooth() band.
The printed summary now includes Slope, Slope_lowCI and Slope_highCI when ci = TRUE.
Documentation now explains how the ribbon is calculated: the slope confidence intervals from smatr are mapped through each group centroid as y = ybar + b_CI * (x - xbar).
ggsmatr 0.1
First public version of the package, with grouped scatter plots and fitted SMA lines from a smatr object.