which
identifies which of the available plots to display. For a sharp
design, the only possibility is 1, the plot of the running variable
against the outcome variable. For a fuzzy design, an additional plot, 2,
may also be displayed, showing the relationship between the running variable and
the treatment variable. Both plots may be displayed with which=c(1,2).
range
the range of values of the running variable for which to plot. This
should be a vector of length two of the format c(min,max). To plot
from the minimum to the maximum value, simply enter c("min","max"). The default
is a window 20 times wider than the first listed bandwidth from the rd object,
truncated by the min/max values of the running variable from the data.