plotqtplot.lmscreg {VGAM}R Documentation

Quantile Plot for LMS Quantile Regression

Description

Plots the quantiles associated with a LMS quantile regression.

Usage

plotqtplot.lmscreg(fitted.values, object, newdata = NULL, 
    percentiles = object@misc$percentiles, lp = NULL, 
    add.arg = FALSE, y = if (length(newdata)) FALSE else TRUE, 
    spline.fit = FALSE, label = TRUE, size.label = 0.06, 
    xlab = NULL, ylab = "",
    pch = par()$pch, pcex = par()$cex, pcol.arg = par()$col,
    xlim = NULL, ylim = NULL,
    llty.arg = par()$lty, lcol.arg = par()$col, llwd.arg = par()$lwd,
    tcol.arg = par()$col, tadj = 1, ...)

Arguments

fitted.values Matrix of fitted values.
object A VGAM quantile regression model, i.e., an object produced by modelling functions such as vglm and vgam with a family function beginning with "lms.", e.g., lms.yjn.
newdata Data frame at which predictions are made. By default, the original data are used.
percentiles Numerical vector with values between 0 and 100 that specify the percentiles (quantiles). The default is to use the percentiles when fitting the model. For example, the value 50 corresponds to the median.
lp Length of percentiles.
add.arg Logical. Add the quantiles to an existing plot?
y Logical. Add the response as points to the plot?
spline.fit Logical. Add a spline curve to the plot?
label Logical. Add the percentiles (as text) to the plot?
size.label Numeric. How much room to leave at the RHS for the label. It is in percent (of the range of the primary variable).
xlab Caption for the x-axis. See par.
ylab Caption for the x-axis. See par.
pch Plotting character. See par.
pcex Character expansion of the points. See par.
pcol.arg Color of the points. See the col argument of par.
xlim Limits of the x-axis. See par.
ylim Limits of the y-axis. See par.
llty.arg Line type. Line type. See the lty argument of par.
lcol.arg Color of the lines. See the col argument of par.
llwd.arg Line width. See the lwd argument of par.
tcol.arg Color of the text (if label is TRUE). See the col argument of par.
tadj Text justification. See the adj argument of par.
... Arguments passed into the plot function when setting up the entire plot. Useful arguments here include main and las.

Details

The above graphical parameters offer some flexibility when plotting the quantiles.

Value

The matrix of fitted values.

Note

While the graphical arguments of this function are useful to the user, this function should not be called directly.

Author(s)

Thomas W. Yee

References

Yee, T. W. (2004) Quantile regression via vector generalized additive models. Statistics in Medicine, 23, 2295–2315.

Documentation accompanying the VGAM package at http://www.stat.auckland.ac.nz/~yee contains further information and examples.

See Also

qtplot.lmscreg.

Examples

## Not run: 
data(bminz)
fit = vgam(BMI ~ s(age, df=c(4,2)), fam=lms.bcn(zero=1), data=bminz)
qtplot(fit)
qtplot(fit, perc=c(25,50,75,95), lcol="blue", tcol="blue", llwd=2)
## End(Not run)

[Package VGAM version 0.7-7 Index]