MethComp {MethComp}R Documentation

Summarize the conversion equations and prediciton intervals between methods.

Description

Takes the results from BA.est, AltReg or MCmcmc and returns a MethComp object, suitable for displaying the relationship between methods in print pr graphic form.

Usage

MethComp(obj)
## S3 method for class 'MethComp':
print(x, digits=4, ... )
## S3 method for class 'MethComp':
plot(x,
                   wh.cmp = 1:2,
                  pl.type = "conv",
                    axlim = range(x$data$y,na.rm=TRUE),
                   points = FALSE,
                     grid = TRUE,
                   N.grid = 10,
                 col.grid = grey(0.9),
                col.lines = "black",
                      eqn = pl.type=="conv" & is.null(attr(x,"Transform")),
                   digits = 1,
                        ... )
## S3 method for class 'MethComp':
lines(x,
                    wh.cmp = getOption("MethComp.wh.cmp"),
                   pl.type = getOption("MethComp.pl.type"),
                     axlim = par("usr")[1:2],
                 col.lines = "black",
                       ... )
## S3 method for class 'MethComp':
points(x,
                     wh.cmp = getOption("MethComp.wh.cmp"),
                    pl.type = getOption("MethComp.pl.type"),
                        ... )

Arguments

obj A MethComp or MCmcmc object.
x A MethComp object.
digits How many digits should be used when displaying conversion equations and variance componenets.
wh.cmp Numeric. Which methods should be plotted.
pl.type Character. If "conv" it will be a plot of two methods against each other, otherwise it will be a plot of the 2nd minus the 1st versus the average; a Bland-Altman type plot.
axlim The extent of the axes.
points Logical. Should the points be included in the plot.
grid Logical. Should there be a grid?
N.grid Numeric. How many gridlines? If a vector of length>1, it will be taken as the position of the gridlines.
col.grid Color of the gridlines.
col.lines Color of the conversion lines.
eqn Logical. Should the conversion equation be printed on the plot.
... Further arguments.

Details

Using MethComp on the results from BA.est or AltReg is not necessary, as these two functions already return objetcs of class MethComp.

plot.MethComp plots the conversion function with prediction limits. It also sets the options "MethComp.wh.cmp" indicating which two methods are plotted and "MethComp.pl.type" indicating whether a plot of methods against each other or a Bland-Altman type plot of differences versus averages.

lines.MethComp and points.MethComp adds conversion lines with prediction limits and points to a plot.

Value

MethComp returns a MethComp object, which is a list with three elements, Conv, a three-way array giving the linear conversion equations between methods, VarComp, a two-way array classified by methods and variance components and data, a copy of the original Meth object supplied.
A MethComp object has an attribute Transform, which is either NULL, or a named list with elements trans and inv, both of which are functions. The first is the transformation applied to measurements before analysis; the results are all given on the transformed scale. The second is the inverse transformation; this is only used when plotting the resulting relationship between methods.
The methods return nothing.

Author(s)

Bendix Carstensen, Steno Diabetes Center, bxc@steno.dk.

See Also

BA.est AltReg MCmcmc

Examples

data( ox )
BA.ox <- BA.est( ox, linked=TRUE )
print( BA.ox )
AR.ox <- AltReg( ox, linked=TRUE  )
print( AR.ox )

[Package MethComp version 0.7.1 Index]