R Graphical Manual

Browse All

Last data update: 2014.03.03

R: Add threshold lines to a plot (two-state setting)

lines.thres2

R Documentation

Add threshold lines to a plot (two-state setting)

Description

The function includes vertical lines for the threshold and confidence interval in a plot created with plot.thres2().

Usage

## S3 method for class 'thres2'
lines(x, ci = TRUE, which.boot = c("norm", "perc"),
  col = 1, lty = c(1, 2), lwd = 1, ...)

Arguments

`x`	an object of class `thres2`.
`ci`	should the confidence interval be plotted? Default, `TRUE`.
`which.boot`	in case `x` contains confidence intervals computed by bootstrapping, which one should be printed? The user can choose between `"norm"` (based on normal distribution) or `"perc"` (based on percentiles). Default, `"norm"`. This argument is ignored if the confidence intervals were computed by the delta method.
`col`	color for the threshold and its corresponding confidence interval. Default, 1.
`lty`	a 2-dimensional vector containing: `lty[1]`: line type for the threshold `lty[2]`: line type for the confidence interval Default, `c(1, 2)`.
`lwd`	line width for the threshold and its corresponding confidence interval. Default, 1.
`...`	further arguments to be passed to `abline()`.

Value

With a plot.thres2 open, this function adds lines for the required threshold.

References

Skaltsa K, Jover L, Carrasco JL. (2010). Estimation of the diagnostic threshold accounting for decision costs and sampling uncertainty. Biometrical Journal 52(5):676-697.

Examples

n1 <- 100
n2 <- 100
set.seed(1234)
par1.1 <- 0
par1.2 <- 1
par2.1 <- 2
par2.2 <- 1
rho <- 0.2
k1 <- rnorm(n1, par1.1, par1.2) # non-diseased
k2 <- rnorm(n2, par2.1, par2.2) # diseased

thres <- thres2(k1, k2, rho, method="eq", ci.method="d")
plot(thres, col=c(1, 2, 4), lwd=c(2, 2, 1), leg.pos="topright")

## Not run: 
thresboot <- thres2(k1, k2, rho, method="emp", ci.method="b")
lines(thresboot, col=3, which.boot="norm")

## End(Not run)