Intercept estimates from segmented relationships

Computes the intercepts of each `segmented' relationship in the fitted model.

Usage

intercept(ogg, parm, rev.sgn = FALSE, var.diff=FALSE,
    .vcov=NULL, .coef=NULL, digits = max(4, getOption("digits") - 2),...)

Arguments

ogg: an object of class "segmented", returned by any segmented method.
parm: the segmented variable whose intercepts have to be computed. If missing all the segmented variables in the model are considered.

rev.sgn: vector of logicals. The length should be equal to the length of parm, but it is recycled otherwise. When TRUE it is assumed that the current parm is `minus' the actual segmented variable, therefore the order is reversed before printing. This is useful when a null-constraint has been set on the last slope.
var.diff: Currently ignored as only point estimates are computed.
.vcov: The full covariance matrix of estimates. If unspecified (i.e. NULL), the covariance matrix is computed internally by vcov(ogg).
.coef: The regression parameter estimates. If unspecified (i.e. NULL), it is computed internally by coef(ogg).
digits: controls number of digits in the returned output.
...: Further arguments to be passed on to vcov.segmented, such as var.diff and is. See Details in vcov.segmented.

Details

A broken-line relationship means that a regression equation exists in the intervals `\(min(x)\) to \(\psi_1\)', `\(\psi_1\) to \(\psi_2\)', and so on. intercept computes point estimates of the intercepts of the different regression equations for each segmented relationship in the fitted model.

Value

intercept returns a list of one-column matrices. Each matrix represents a segmented relationship.

Author

Vito M. R. Muggeo, vito.muggeo@unipa.it

Examples

## see ?slope
if (FALSE) { # \dontrun{
intercept(out.seg)
} # }