Bars for interval estimate of the breakpoints

Draws bars relevant to breakpoint estimates (point estimate and confidence limits) on the current device

Usage

# S3 method for class 'segmented'
lines(x, term, bottom = TRUE, shift=FALSE, conf.level = 0.95, k = 50, 
    pch = 18, rev.sgn = FALSE, .vcov=NULL, .coef=NULL, ...)

Arguments

x

an object of class segmented.

term

the segmented variable of the breakpoints being drawn. It may be unspecified when there is a single segmented variable.

bottom

logical, indicating if the bars should be plotted at the bottom (TRUE) or at the top (FALSE).

shift

logical, indicating if the bars should be `shifted' on the y-axis before plotting. Useful for multiple breakpoints with overlapped confidence intervals.

conf.level

the confidence level of the confidence intervals for the breakpoints.

k

a positive integer regulating the vertical position of the drawn bars. See Details.

pch

either an integer specifying a symbol or a single character to be used in plotting the point estimates of the breakpoints. See points.

rev.sgn

should the signs of the breakpoint estimates be changed before plotting? see Details.

.vcov

The full covariance matrix of estimates. If unspecified (i.e. NULL), the covariance matrix is computed internally by vcov(x).

.coef

The regression parameter estimates. If unspecified (i.e. NULL), it is computed internally by coef(x).

...

further arguments passed to arrows, for instance `col' that can be a vector.

Details

lines.segmented simply draws on the current device the point estimates and relevant confidence limits of the estimated breakpoints from a "segmented" object. The y coordinate where the bars are drawn is computed as usr[3]+h if bottom=TRUE or usr[4]-h when bottom=FALSE, where h=(usr[4]-usr[3])/abs(k) and usr are the extremes of the user coordinates of the plotting region. Therefore for larger values of k the bars are plotted on the edges. The argument rev.sgn allows to change the sign of the breakpoints before plotting. This may be useful when a null-right-slope constraint is set.

See also

plot.segmented to plot the fitted segmented lines, and points.segmented to add the fitted joinpoints.

Examples

## See ?plot.segmented