Create a Q-Q Gaussian graph of the residuals of a cgOneFactorFit object
# S4 method for cgOneFactorFit
qqGraph(fit, line=NULL, cgtheme = TRUE, device = "single", ...)qqGraph.cgOneFactorFit returns
an invisible NULL. The main purpose is the side
effect of graphing to the current device.
A fit object of class cgOneFactorFit.
Add a line through the estimated 25th and 75th percentiles.
When set to the default NULL, the addition
of a line depends on the following: When there is no censored
data, the line will be added with the qqline algorithm.
If any censored data residuals are present, no line is added unless
line=TRUE is explicitly specified below.
When set to the default TRUE, ensures a trellis device is active with
limited color scheme. Namely, background,
strip.shingle, and strip.background are each set to "white".
Can be one of three values:
"single"The default, which will put all graphs on the same
device page. For example, when resistant & robust and classical
least squares are present and model="both" (the default),
a 2 x 1 paneled graph will be created.
"multiple"Relevant only when resistant & robust and classical
least squares are present and model="both" (the default) or
model="extended". In
those cases, a new graphics device is generated to hold the resistant & robust
version, as a single-paneled graph,
and the classical least squares version is on the previous device.
If model="extended", then
a second new graphics device is generated to hold the unweighted
resistant & robust residuals, as another single-paneled graph.
"ask"Relevant only when resistant & robust and classical
least squares are present and model="both" (the default) or
model="extended". In
that case, each are portrayed as a single-paneled graph, with the
ask=TRUE argument specified in par so that
the user input confirmation is needed before the graphs are
drawn.
Additional arguments. One is currently valid:
model For cgOneFactorFit fit objects that have
classical least squares lm() or resistant & robust
rlm() fits, the following argument values are possible:
"both"Q-Q graphs of the residuals from both the ordinary
classical least squares and resistant & robust fits are
plotted. This is the default when both fits are present in
the cgOneFactorFit object specified in the fit
argument. If the resistant & robust fit is not available,
this value is not relevant.
"olsonly"Only a Q-Q graph of the residuals from
the ordinary
classical least squares olsfit fit is performed.
"rronly" or "rrwtdonly"Only a Q-Q graph of the
weighted residuals from
the resistant and
robust rrfit fit is plotted.
"rrunwtdonly"Only a Q-Q graph of the unweighted
residuals from
the resistant and
robust rrfit fit is plotted.
For other possible cgOneFactorFit fit slots such as
accelerated failure time or unequal variance models, the model
argument is not relevant, and the appropriate Q-Q graph will
be plotted for these model types.
Bill Pikounis [aut, cre, cph], John Oleynick [aut], Eva Ye [ctb]
For censored data residuals, left-censored values are shown as a shallow "V", which is actually just a rotated downward "<" sign. Similarly, right-censored values are shown as a deeper "^", which is a rotated upwared ">" sign.
For the line argument, an added line when censored data residuals
are present needs to be interpreted very cautiously. If "too many"
censored data values are present, the line will appear nonsensical if
indeed it can even be estimated with 25th and 75th percentiles in the
presence of the the censored data residuals. These percentiles are
estimated via the Kaplan-Meier method as proposed by Gentleman and Crowley
(1991), with the survival::survfit function.
The heading for the graph is taken from the cgOneFactorData object,
which prepareCGOneFactorData sets from its analysisname
argument.
The label for the Y-axis of residuals is derived from the cgOneFactorData object,
which prepareCGOneFactorData sets from its endptname
argument.
The number of decimal places printed in the ticks on the Y-axis is taken
from the cgOneFactorData object,
which prepareCGOneFactorData sets from its digits
argument.
The minimum and maximum values from the range of the residuals are respectively labeled in the bottom and top left corners of the graph region.
Gentleman, R.C. and Crowley, J. (1991). "Graphical Methods for Censored Data", Journal of the American Statistical Association, Volume 86, 678-683.
data(canine)
canine.data <- prepareCGOneFactorData(canine, format="groupcolumns",
analysisname="Canine",
endptname="Prostate Volume",
endptunits=expression(plain(cm)^3),
digits=1, logscale=TRUE, refgrp="CC")
canine.fit <- fit(canine.data)
qqGraph(canine.fit)
qqGraph(canine.fit, model="olsonly")
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