plot.nestedLogit: Plotting Nested Logit Models

Description

A plot method for "nestedLogit" objects produced by the nestedLogit function. Fitted probabilities under the model are plotted for each level of the polytomous response variable, with one of the explanatory variables on the horizontal axis and other explanatory variables fixed to particular values. By default, a 95% pointwise confidence envelope is added to the plot.

Usage

# S3 method for nestedLogit
plot(
  x,
  x.var,
  others,
  n.x.values = 100L,
  xlab = x.var,
  ylab = "Fitted Probability",
  main,
  cex.main = 1,
  digits.main = getOption("digits") - 2L,
  font.main = 1L,
  pch = 1L:length(response.levels),
  lwd = 3,
  lty = 1L:length(response.levels),
  col = palette()[1L:length(response.levels)],
  legend = TRUE,
  legend.inset = 0.01,
  legend.location = "topleft",
  legend.bty = "n",
  conf.level = 0.95,
  conf.alpha = 0.3,
  ...
)

Value

NULL Used for its side-effect of producing a plot

Arguments

x: an object of "nestedLogit" produced by nestedLogit.
x.var: quoted name of the variable to appear on the x-axis; if omitted, the first predictor in the model is used.
others: a named list of values for the other variables in the model, that is, other than x.var; if any other predictor is omitted, it is set to an arbitrary value---the mean for a numeric predictor or the first level or value of a factor, character, or logical predictor; only one value may be specified for each variable in others.
n.x.values: the number of evenly spaced values of x.var at which to evaluate fitted probabilities to be plotted (default 100).
xlab: label for the x-axis (defaults to the value of x.var).
ylab: label for the y-axis (defaults to "Fitted Probability").
main: main title for the graph (if missing, constructed from the variables and values in others).
cex.main: size of main title (see par).
digits.main: number of digits to retain when rounding values for the main title.
font.main: font for main title (see par).
pch: plotting characters (see par).
lwd: line width (see par).
lty: line types (see par).
col: line colors (see par).
legend: if TRUE (the default), add a legend for the response levels to the graph.
legend.inset: default 0.01 (see legend).
legend.location: position of the legend (default "topleft", see legend).
legend.bty: the type of box to be drawn around the legend. The allowed values are "o" (the default) and "n".
conf.level: the level for pointwise confidence envelopes around the predicted response probabilities; the default is .0.95. If NULL, the confidence envelopes are suppressed.
conf.alpha: the opacity of the confidence envelopes; the default is 0.3.
...: arguments to be passed to matplot.

Author

John Fox jfox@mcmaster.ca

Examples

Run this code

data("Womenlf", package = "carData")
m <- nestedLogit(partic ~ hincome + children,
                 logits(work=dichotomy("not.work", c("parttime", "fulltime")),
                        full=dichotomy("parttime", "fulltime")),
                        data=Womenlf)
plot(m, legend.location="top")
op <- par(mfcol=c(1, 2), mar=c(4, 4, 3, 1) + 0.1)
plot(m, "hincome", list(children="absent"),
     xlab="Husband's Income", legend=FALSE)
plot(m, "hincome", list(children="present"),
     xlab="Husband's Income")
par(op)