Points method for segmented objects

Takes a fitted segmented object returned by segmented() and adds on the current plot the joinpoints of the fitted broken-line relationships.

Usage

# S3 method for class 'segmented'
points(x, term, interc = TRUE, link = TRUE, rev.sgn=FALSE, 
    transf=I, .vcov=NULL, .coef=NULL, const=0, v=TRUE, ...)

Arguments

x

an object of class segmented.

term

the segmented variable of interest. It may be unspecified when there is a single segmented variable.

interc

If TRUE the computed joinpoints include the model intercept (if it exists).

link

when TRUE (default), the fitted joinpoints are plotted on the link scale

rev.sgn

when TRUE, the fitted joinpoints are plotted on the `minus' scale of the current term variable. This is useful when a null-constraint has been set on the last slope.

transf

A possible function to convert the fitted values before plotting.

.vcov

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

.coef

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

const

A constant to be added (on the y-scale) to the values before transforming and plotting.

v

logical. If TRUE, vertical lines at the breakpoints are also drawn.

...

other graphics parameters to pass on to points() and segments() (if v=TRUE).

Details

We call 'joinpoint' the plane point having as coordinates the breakpoints (on the x scale) and the fitted values of the segmented relationship at that breakpoints (on the y scale). points.segmented() simply adds the fitted joinpoints on the current plot. This could be useful to emphasize the changes of the piecewise linear relationship.

See also

plot.segmented to plot the fitted segmented lines.

Examples

if (FALSE) { # \dontrun{
#see examples in ?plot.segmented
} # }