rddensity: Manipulation Testing Based on Density Discontinuity

Density discontinuity test (a.k.a.  manipulation test) is commonly employed in regression discontinuity designs and other program evaluation settings to detect whether there is evidence of perfect self-selection (manipulation) around a cutoff where a treatment/policy assignment changes.  This package provides tools for conducting the aforementioned statistical test: rddensity() to construct local polynomial based density discontinuity test given a prespecified cutoff, rdbwdensity() to perform bandwidth selection, and rdplotdensity() to construct density plot near the cutoff.