plotqtplot.lmscreg: Quantile Plot for LMS Quantile Regression
In VGAM: Vector Generalized Linear and Additive Models

plotqtplot.lmscreg

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.

Examples

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

## End(Not run)

VGAM documentation built on Sept. 18, 2024, 9:09 a.m.