car (version 0.8-1)

ceres.plots: Ceres Plots

Description

These functions calculate Ceres plots for linear and generalized linear model.

Usage

ceres.plots(model, variable, ask=missing(variable), one.page=!ask, 
  span=0.5, ...)

ceres.plot(model, ...)

ceres.plot.lm(model, variable, line=T, smooth=T, span=0.5, 
  las=1, col=palette()[2], pch=1, lwd=2, iter, main="ceres Plot", ...)

ceres.plot.glm(model, ...)

Arguments

model

model object produced by lm or glm.

variable

variable (if it exists in the search path) or name of variable. This argument usually is omitted for ceres.plots.

ask

if TRUE, a menu is provided in the R Console for the user to select the variable(s) to plot, and to modify the span for the smoother used to draw a nonparametric-regression line on the plot.

one.page

if TRUE (and ask=F), put all plots on one graph.

span

span for lowess smoother.

line

TRUE to plot least-squares line.

smooth

TRUE to plot nonparametric-regression (lowess) line.

las

if 0, ticks labels are drawn parallel to the axis; set to 1 (the default) for horizontal labels (see par).

col

color for points and lines; the default is the second entry in the current color palette (see palette and par).

pch

plotting character for points; default is 1 (a circle, see par).

lwd

line width; default is 2 (see par).

iter

number of robustness iterations for nonparametric-regression smooth; defaults to 3 for a linear model and to 0 for a non-Gaussian glm.

main

title for plot.

...

not for the user.

Value

• NULL. These functions are used for their side effect: producing plots.

Details

Ceres plots are a generalization of component+residual (partial residual) plots that are less prone to leakage of nonlinearity among the predictors. The function intended for direct use is ceres.plots. By default, this function is used interactively through a text menu. The model cannot contain interactions, but can contain factors. Factors may be present in the model, but Ceres plots cannot be drawn for them.

References

Cook, R. D. and Weisberg, S. (1999) Applied Regression, Including Computing and Graphics. Wiley. Fox, J. (1997) Applied Regression, Linear Models, and Related Methods. Sage.

See Also

cr.plots, av.plots

Examples

data(Prestige)
ceres.plots(lm(prestige~income+education+type, data=Prestige))