DCdensity: McCrary Sorting Test

In rdd: Regression Discontinuity Estimation

Description

DCdensity implements the McCrary (2008) sorting test.

Usage

DCdensity(runvar, cutpoint, bin = NULL, bw = NULL, verbose = FALSE,
  plot = TRUE, ext.out = FALSE, htest = FALSE)

Arguments

runvar	numerical vector of the running variable
cutpoint	the cutpoint (defaults to 0)
bin	the binwidth (defaults to 2*sd(runvar)*length(runvar)^(-.5))
bw	the bandwidth to use (by default uses bandwidth selection calculation from McCrary (2008))
verbose	logical flag specifying whether to print diagnostic information to the terminal. (defaults to FALSE)
plot	logical flag indicating whether to plot the histogram and density estimations (defaults to TRUE). The user may wrap this function in additional graphical options to modify the plot.
ext.out	logical flag indicating whether to return extended output. When FALSE (the default) DCdensity will return only the p-value of the test. When TRUE, DCdensity will return the additional information documented below.
htest	logical flag indicating whether to return an "htest" object compatible with base R's hypothesis test output.

Value

If ext.out is FALSE, only the p value will be returned. Additional output is enabled when ext.out is TRUE. In this case, a list will be returned with the following elements:

theta	the estimated log difference in heights at the cutpoint
se	the standard error of theta
z	the z statistic of the test
p	the p-value of the test. A p-value below the significance threshhold indicates that the user can reject the null hypothesis of no sorting.
binsize	the calculated size of bins for the test
bw	the calculated bandwidth for the test
cutpoint	the cutpoint used
data	a dataframe for the binning of the histogram. Columns are cellmp (the midpoints of each cell) and cellval (the normalized height of each cell)

Author(s)

Drew Dimmery <[e-mail]>

References

McCrary, Justin. (2008) "Manipulation of the running variable in the regression discontinuity design: A density test," Journal of Econometrics. 142(2): 698-714. http://dx.doi.org/10.1016/j.jeconom.2007.05.005

Examples

#No discontinuity
x<-runif(1000,-1,1)
DCdensity(x,0)

#Discontinuity
x<-runif(1000,-1,1)
x<-x+2*(runif(1000,-1,1)>0&x<0)
DCdensity(x,0)

Example output

Loading required package: sandwich
Loading required package: lmtest
Loading required package: zoo

Attaching package: 'zoo'

The following objects are masked from 'package:base':

    as.Date, as.Date.numeric

Loading required package: AER
Loading required package: car
Loading required package: survival
Loading required package: Formula
[1] 0.4929004
[1] 1.436159e-08

rdd documentation built on May 2, 2019, 10:22 a.m.