plot.nestedLogit {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 class '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,
  ...
)

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.

Value

NULL Used for its side-effect of producing a plot

Author(s)

John Fox [e-mail]

See Also

nestedLogit, matplot

Examples

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)