Plots the power-by-samplesize data.frames returned by the power functions.
# S3 method for power_by_samplesize
plot(x, crit_power = NULL, plot_dir = NULL, ...)list, results of a power function
numeric, critical power value one is looking for (adds a line and the critical sample size to the plot)
character, name of an existing directory where the power plots should be saved to (leaving it NULL will plot to the default device)
additional parameters, not used at the moment