# plotPlacebo: Draw a (density) plot of placebo tests In rddtools: Toolbox for Regression Discontinuity Design ('RDD')

## Description

Draw a plot of placebo tests, estimating the impact on fake cutpoints

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16``` ```plotPlacebo(object, device = c("ggplot", "base"), ...) ## S3 method for class 'rdd_reg' plotPlacebo(object, device = c("ggplot", "base"), from = 0.25, to = 0.75, by = 0.1, level = 0.95, same_bw = FALSE, vcov. = NULL, plot = TRUE, output = c("data", "ggplot"), ...) plotPlaceboDens(object, device = c("ggplot", "base"), ...) ## S3 method for class 'rdd_reg' plotPlaceboDens(object, device = c("ggplot", "base"), from = 0.25, to = 0.75, by = 0.1, level = 0.95, same_bw = FALSE, vcov. = NULL, ...) computePlacebo(object, from = 0.25, to = 0.75, by = 0.1, level = 0.95, same_bw = FALSE, vcov. = NULL) ```

## Arguments

 `object` the output of an RDD regression `device` Whether to draw a base or a ggplot graph. `from` Starting point of the fake cutpoints sequence. Refers ot the quantile of each side of the true cutpoint `to` Ending point of the fake cutpoints sequence. Refers ot the quantile of each side of the true cutpoint `by` Increments of the from-to sequence `level` Level of the confidence interval shown `same_bw` Whether to re-estimate the bandwidth at each point `vcov.` Specific covariance function to pass to coeftest. See help of package `sandwich`. `plot` Whether to actually plot the data. `output` Whether to return (invisibly) the data frame containing the bandwidths and corresponding estimates, or the ggplot object `...` Further arguments passed to specific methods.

## Value

A data frame containing the cutpoints, their corresponding estimates and confidence intervals.

## Author(s)

Matthieu Stigler <[email protected]>

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10``` ```data(house) house_rdd <- rdd_data(y=house\$y, x=house\$x, cutpoint=0) reg_nonpara <- rdd_reg_np(rdd_object=house_rdd) plotPlacebo(reg_nonpara) # Use with another vcov function; cluster case reg_nonpara_lminf <- rdd_reg_np(rdd_object=house_rdd, inference='lm') # need to be a function applied to updated object! vc <- function(x) vcovCluster(x, clusterVar=model.frame(x)\$x) plotPlacebo(reg_nonpara_lminf, vcov. = vc) ```

### Example output

```Loading required package: AER

Attaching package: 'zoo'

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

as.Date, as.Date.numeric