HeckmanEM.envelope {HeckmanEM}

Envelope for the Heckman Selection model

Description

'HeckmanEM.envelope()' plots the envelope for the fitted Heckman selection model.

Usage

HeckmanEM.envelope(obj, envelope = 0.95, ...)

Arguments

obj

An object of the class HeckmanEM.

envelope

The envelope coverage percentage.

...

Other option for chart.QQPlot from PerformanceAnalytics package.

Value

A residual plot of the fitted data and its envelope.

Examples

n <- 100
family <- "T"
nu <- 4
rho <- .6
cens <- .25

set.seed(20200527)
w <- cbind(1,runif(n,-1,1),rnorm(n))
x <- cbind(w[,1:2])
c <- qt(cens, df=nu)

sigma2 <- 1

beta <- c(1,0.5)
gamma <- c(1,0.3,-.5)
gamma[1] <- -c*sqrt(sigma2)

set.seed(1)
datas <- rHeckman(x,w,beta,gamma,sigma2,rho,nu,family=family)
y <- datas$y
cc <- datas$cc

res <- HeckmanEM(y, x, w, cc, nu = 4, family = "Normal", error = 1e-05, iter.max = 500,
                 im = TRUE, criteria = TRUE)
HeckmanEM.envelope(res, ylab="Normalized Quantile Residuals",xlab="Standard normal quantile",
                   line="quartile", col=c(20,1), pch=19, ylim = c(-5,4))