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EnvStats (version 2.1.0)

plot.gofTwoSample: Plot Results of Goodness-of-Fit Test to Compare Two Samples

Description

Plot the results of calling the function gofTest to compare two samples. gofTest returns an object of class "gofTwoSample" when supplied with both the arguments y and x. plot.gofTwoSample provides five different kinds of plots. The function plot.gofTwoSample is automatically called by plot when given an object of class "gofTwoSample". The names of other functions associated with goodness-of-fit test are listed under Goodness-of-Fit Tests.

Usage

## S3 method for class 'gofTwoSample':
plot(x, plot.type = "Summary", 
    captions = list(PDFs = NULL, CDFs = NULL, QQ = NULL, MDQQ = NULL, Results = NULL), 
    x.labels = list(PDFs = NULL, CDFs = NULL, QQ = NULL, MDQQ = NULL), 
    y.labels = list(PDFs = NULL, CDFs = NULL, QQ = NULL, MDQQ = NULL), 
    same.window = FALSE, ask = same.window & plot.type == "All", x.points.col = "blue", 
    y.points.col = "black", points.pch = 1, jitter.points = TRUE, discrete = FALSE, 
    plot.pos.con = 0.375, x.ecdf.col = "blue", y.ecdf.col = "black", 
    x.ecdf.lwd = 3 * par("cex"), y.ecdf.lwd = 3 * par("cex"), x.ecdf.lty = 1, 
    y.ecdf.lty = 4, add.line = TRUE, 
    digits = ifelse(plot.type == "Summary", 2, .Options$digits), test.result.font = 1, 
    test.result.cex = ifelse(plot.type == "Summary", 0.9, 1) * par("cex"), 
    test.result.mar = c(0, 0, 3, 0) + 0.1, 
    cex.main = ifelse(plot.type == "Summary", 1.2, 1.5) * par("cex"), 
    cex.axis = ifelse(plot.type == "Summary", 0.9, 1) * par("cex"), 
    cex.lab = ifelse(plot.type == "Summary", 0.9, 1) * par("cex"), 
    main = NULL, xlab = NULL, ylab = NULL, xlim = NULL, ylim = NULL, 
    add.om.title = TRUE, 
    oma = if (plot.type == "Summary" & add.om.title) c(0, 0, 4, 0) else c(0, 0, 0, 0), 
    om.title = NULL, om.font = 2, om.cex.main = 1.5 * par("cex"), om.line = 0, ...)

Arguments

x
an object of class "gof". See gof.object for details.
plot.type
character string indicating what kind of plot to create. Only one particular plot type will be created, unless plot.type="All", in which case all plots will be created sequentially. The possible values of plot.type are:
captions
a list with 1 to 5 components with the names "PDFs", "CDFs", "QQ", "MDQQ", and/or "Results". Each component either has the value NULL or else it is a character string c
x.labels
a list of 1 to 4 components with the names "PDFs", "CDFs", "QQ", and/or "MDQQ". Each component either has the value NULL or else it is a character string containing the label for th
y.labels
a list of 1 to 4 components with the names "PDFs", "CDFs", "QQ", and/or "MDQQ". Each component either has the value NULL or else it is a character string containing the label for th
same.window
logical scalar indicating whether to produce all plots in the same graphics window (same.window=TRUE), or to create a new graphics window for each separate plot (same.window=FALSE; the default). The argument is relev
ask
logical scalar supplied to the function devAskNewPage, indicating whether to prompt the user before creating a new plot within a single graphics window. The default value is FALSE
x.points.col
a character string or numeric scalar determining the color of the plotting symbol used to display the distribution of the observed x values that were supplied to gofTest. The defa
y.points.col
a character string or numeric scalar determining the color of the plotting symbol used to display the distribution of the observed y values that were supplied to gofTest. The defau
points.pch
a character string or numeric scalar determining the plotting symbol used to display the distribution of the observed x and y values that were supplied to gofTest. The
jitter.points
logical scalar indicating whether to jitter the points in the strip chart. The default value is jitter.points=TRUE.
discrete
logical scalar indicating whether the two distributions are considered to be discrete (discrete=TRUE) or not(discrete=FALSE; the default). When discrete=TRUE, the empirical CDFs are plotted as step functions
plot.pos.con
numeric scalar between 0 and 1 containing the value of the plotting position constant used to construct the observed (empirical) CDFs. The default value is plot.pos.con=0.375. See the help files for
x.ecdf.col
a character string or numeric scalar determining the color of the line used to display the empirical CDF for the x values that were supplied to gofTest. The default value is
y.ecdf.col
a character string or numeric scalar determining the color of the line used to display the empirical CDF for the y values that were supplied to gofTest. The default value is
x.ecdf.lwd
numeric scalar determining the width of the line used to display the empirical CDF for the x values that were supplied to gofTest. The default value is x.ecdf.lwd=3*par("cex")
y.ecdf.lwd
numeric scalar determining the width of the line used to display the empirical CDF for the y values that were supplied to gofTest. The default value is y.ecdf.lwd=3*par("cex")
x.ecdf.lty
numeric scalar determining the line type used to display the empirical CDF for the x values that were supplied to gofTest. The default value is x.ecdf.lty=1. See the
y.ecdf.lty
numeric scalar determining the line type used to display the empirical CDF for the y values that were supplied to gofTest. The default value is y.ecdf.lty=4. See the
add.line
logical scalar indicating whether to add a line to the plot. If add.line=TRUE and plot.type="Q-Q Plot", a 0-1 line is added to the plot. If add.line=TRUE and plot.type="Tukey M-D Q-Q Plot", a h
digits
scalar indicating how many significant digits to print for the test results when plot.type="Summary" or plot.type="Test Results". If plot.type == "Summary", the default value is digits=2, ot
test.result.font
numeric scalar indicating which font to use to print out the test results. The default value is test.result.font=1. See the description of the font argument in the help file for par
test.result.cex
numeric scalar indicating the value of cex to use to print out the test results. The default value is 0.9*par("cex") when plot.type="Summary", otherwise it is par("cex"). See the description
test.result.mar
numeric vector indicating the value of mar to use to print out the test results. The default value is test.result.mar=c(0, 0, 3, 0)+0.1. See the description of the mar argument in the help file for
add.om.title
logical scalar indicating whether to add a title in the outer margin when plot.type="Summary". The default value is add.om.title=TRUE.
om.title
character string containing the outer margin title. The default value is om.title=NULL, which will result in a default title.
om.font
numeric scalar indicating the font to use for the outer margin. The default value is om.font=2.
om.cex.main
numeric scalar indicating the value of cex for the outer margin title. The default value is 1.75 * par("cex").
om.line
numeric scalar indicating the line to place the outer margin title on. The default value is om.line=0.5.
cex.main, cex.axis, cex.lab, main, xlab, ylab, xlim, ylim, oma, ...
additional graphics parameters. See the help file for par.

Value

  • plot.gofTwoSample invisibly returns the first argument, x.

Details

The function plot.gofTwoSample is a method for the generic function plot for the class "gofTwoSample" (see gofTwoSample.object). It can be invoked by calling plot and giving it an object of class "gofTwoSample" as the first argument, or by calling plot.gofTwoSample directly, regardless of the class of the object given as the first argument to plot.gofTwoSample. Plots associated with the goodness-of-fit test are produced on the current graphics device. These can be one or all of the following:
  • Observed distributions (plot.type="PDFs: Observed").
  • Observed CDFs (plot.type="CDFs: Observed"). See the help file forcdfCompare.
  • Q-Q Plot (plot.type="Q-Q Plot"). See the help file forqqPlot.
  • Tukey mean-difference Q-Q plot (plot.type="Tukey M-D Q-Q Plot"). See the help file forqqPlot.
  • Results of the goodness-of-fit test (plot.type="Test Results"). See the help file forprint.gofTwoSample.
See the help file for gofTest for more information.

References

Chambers, J. M. and Hastie, T. J. (1992). Statistical Models in S. Wadsworth & Brooks/Cole.

See Also

gofTest, gofTwoSample.object, print.gofTwoSample, Goodness-of-Fit Tests, plot.

Examples

Run this code
# Create an object of class "gofTwoSample" then plot the results.
  # (Note: the call to set.seed simply allows you to reproduce 
  # this example.)

  set.seed(300) 
  dat1 <- rnorm(20, mean = 3, sd = 2) 
  dat2 <- rnorm(10, mean = 1, sd = 2) 
  gof.obj <- gofTest(x = dat1, y = dat2) 

  # Summary plot (the default)
  #---------------------------
  dev.new()
  plot(gof.obj)


  # Make your own titles for the summary plot
  #------------------------------------------
  dev.new()
  plot(gof.obj, captions = list(PDFs = "Compare PDFs", 
    CDFs = "Compare CDFs", QQ = "Q-Q Plot", Results = "Results"),
    om.title = "Summary Plot")


  # Just the Q-Q Plot
  #------------------
  dev.new()
  plot(gof.obj, plot.type="Q-Q")


  # Make your own title for the Q-Q Plot
  #-------------------------------------
  dev.new()
  plot(gof.obj, plot.type="Q-Q", main = "Q-Q Plot")

  #==========

  # Clean up
  #---------
  rm(dat1, dat2, gof.obj)
  graphics.off()

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