R: Density Plot for LMS Quantile Regression

plotdeplot.lmscreg {VGAM} | R Documentation

## Density Plot for LMS Quantile Regression

### Description

Plots a probability density function associated with a LMS quantile regression.

### Usage

    plotdeplot.lmscreg(answer, y.arg, add.arg = FALSE,
        xlab = "", ylab = "density", xlim = NULL, ylim = NULL,
        llty.arg = par()$lty, col.arg = par()$col,
        llwd.arg = par()$lwd, ...)

### Arguments

`answer` | Output from functions of the form `deplot.???` where `???` is the name of the VGAM LMS family function, e.g., `lms.yjn`. See below for details.
`y.arg` | Numerical vector. The values of the response variable at which to evaluate the density. This should be a grid that is fine enough to ensure the plotted curves are smooth.
`add.arg` | Logical. Add the density to an existing plot?
`xlab, ylab` | Caption for the x- and y-axes. See `par`.
`xlim, ylim` | Limits of the x- and y-axes. See `par`.
`llty.arg` | Line type. See the `lty` argument of `par`.
`col.arg` | Line color. See the `col` argument of `par`.
`llwd.arg` | Line width. See the `lwd` 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 list `answer`, which has components

`newdata` | The argument `newdata` above from the argument list of `deplot.lmscreg`, or a one-row data frame constructed out of the `x0` argument.
`y` | The argument `y.arg` above.
`density` | Vector of the density function values evaluated at `y.arg`.

### 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.

### See Also

`deplot.lmscreg`.

### Examples

    fit <- vgam(BMI ~ s(age, df = c(4,2)), lms.bcn(zero = 1), bmi.nz)
    ## Not run:  y = seq(15, 43, by = 0.25)
    deplot(fit, x0 = 20, y = y, xlab = "BMI", col = "green", llwd = 2,
           main = "BMI distribution at ages 20 (green), 40 (blue), 60 (orange)")
    deplot(fit, x0 = 40, y = y, add = TRUE, col = "blue", llwd = 2)
    deplot(fit, x0 = 60, y = y, add = TRUE, col = "orange", llwd = 2) -> aa

    names(aa@post$deplot)
    aa@post$deplot$newdata
    head(aa@post$deplot$y)
    head(aa@post$deplot$density)
    ## End(Not run)

[Package VGAM version 1.1-3 Index]