av.plots

From car v1.2-10 by John Fox

Added-Variable Plots

These functions construct added-variable (also called partial-regression) plots for linear and generalized linear models.

Keywords: hplot, regression

Usage

av.plots(model, variable, ask=missing(variable), one.page=!ask, ...)

avp(...)

av.plot(model, ...)

## S3 method for class 'lm':
av.plot(model, variable, 
  labels=names(residuals(model)[!is.na(residuals(model))]), 
  identify.points=TRUE, las=par("las"), col=palette()[2], pch=1, lwd=2,
  main="Added-Variable Plot", ...)

## S3 method for class 'glm':
av.plot(model, variable, 
    labels=names(residuals(model)[!is.na(residuals(model))]), 
    identify.points=TRUE, las=par("las"), col=palette()[2], pch=1, lwd=2, 
    main="Added-Variable Plot", type=c("Wang", "Weisberg"), ...)

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 avp or av.plots.
ask: if TRUE, a menu is provided in the R Console for the user to select the term(s) to plot.
one.page: if TRUE (and ask=FALSE), put all plots on one graph.
labels: observation names.
identify.points: if TRUE, then identify points interactively.
las: if 0, ticks labels are drawn parallel to the axis; set to 1 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).
main: title for plot.
type: if "Wang" use the method of Wang (1985); if "Weisberg" use the method in the Arc software associated with Cook and Weisberg (1999).
...: arguments to be passed down to av.plot.lm or av.plot.glm.

Details

The function intended for direct use is av.plots (for which avp is an abbreviation). By default, these functions are used interactively through a text menu. The model can contain factors and interactions. An added-variable plot can be drawn for each column of the model matrix, including the constant.

Value

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

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. Wang, P C. (1985) Adding a variable in generalized linear models. Technometrics 27, 273--276.

Examples

av.plots(lm(prestige~income+education+type, data=Duncan))

av.plots(glm(partic != "not.work" ~ hincome + children, 
  data=Womenlf, family=binomial))

Documentation reproduced from package car, version 1.2-10, License: GPL (>= 2)

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