QuantileQuantile (QQ) Graphs of a cgOneFactorFit object
Description
Create a QQ Gaussian graph of the residuals of a cgOneFactorFit object
Usage
Arguments
fit 
A fit object of class cgOneFactorFit .

line 
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.

cgtheme 
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" .

device 
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 singlepaneled 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 singlepaneled 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 singlepaneled 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" QQ 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 QQ graph of the residuals from
the ordinary
classical least squares olsfit fit is performed.
"rronly" or "rrwtdonly" Only a QQ graph of the
weighted residuals from
the resistant and
robust rrfit fit is plotted.
"rrunwtdonly" Only a QQ 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 QQ graph will
be plotted for these model types.

Details
For censored data residuals, leftcensored values are shown as a shallow "V",
which is actually just a rotated downward "<" sign. Similarly, rightcensored
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 KaplanMeier 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 Yaxis 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 Yaxis 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.
Value
qqGraph.cgOneFactorFit
returns
an invisible NULL
. The main purpose is the side
effect of graphing to the current device.
Note
Contact cg@billpikounis.net for bug reports, questions,
concerns, and comments.
Author(s)
Bill Pikounis [aut, cre, cph], John Oleynick [aut], Eva Ye [ctb]
References
Gentleman, R.C. and Crowley, J. (1991). "Graphical Methods for Censored
Data", Journal of the American Statistical Association, Volume
86, 678683.
See Also
qqline
Examples