R: Density Plot for LMS Quantile Regression

deplot.lmscreg {VGAM} | R Documentation

## Density Plot for LMS Quantile Regression

### Description

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

### Usage

    deplot.lmscreg(object, newdata = NULL, x0, y.arg, show.plot = TRUE, ...)

### Arguments

`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` | Optional data frame containing secondary variables such as sex. It should have a maximum of one row. The default is to use the original data.
`x0` | Numeric. The value of the primary variable at which to make the ‘slice’.
`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.
`show.plot` | Logical. Plot it? If `FALSE` no plot will be done.
`...` | Graphical parameter that are passed into `plotdeplot.lmscreg`.

### Details

This function calls, e.g., `deplot.lms.yjn` in order to compute the density function.

### Value

The original `object` but with a list placed in the slot `post`, called `@post$deplot`. The list has components

`newdata` | The argument `newdata` above, 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

`plotdeplot.lmscreg` actually does the plotting.

### 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

`plotdeplot.lmscreg`, `qtplot.lmscreg`, `lms.bcn`, `lms.bcg`, `lms.yjn`.

### Examples

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

    names(a@post$deplot)
    a@post$deplot$newdata
    head(a@post$deplot$y)
    head(a@post$deplot$density)

    ## End(Not run)

[Package VGAM version 1.0-3 Index]