R: Plots the centile curves for a GAMLSS object

centiles {gamlss} | R Documentation

## Plots the centile curves for a GAMLSS object

### Description

This function `centiles()` plots centiles curves for distributions belonging to the GAMLSS family of distributions. The function also tabulates the sample percentages below each centile curve (for comparison with the model percentages given by the argument `cent`.) The function `centiles.fan()` plots a fan-chart of the centile curves. A restriction of the functions is that it applies to models with one explanatory variable only.

### Usage

    centiles(obj, xvar = NULL, cent = c(0.4, 2, 10, 25, 50, 75, 90, 98, 99.6),
             legend = TRUE, ylab = "y", xlab = "x", main = NULL,
             main.gsub = "@", xleg = min(xvar), yleg = max(obj$y),
             xlim = range(xvar), ylim = range(obj$y), save = FALSE,
             plot = TRUE, points = TRUE,  pch =  15, cex = 0.5, col =  gray(0.7),
             col.centiles = 1:length(cent) + 2, lty.centiles = 1, lwd.centiles = 1, ...)
    centiles.fan(obj, xvar = NULL, cent = c(0.4, 2, 10, 25, 50, 75, 90, 98, 99.6),
             ylab = "y", xlab = "x", main = NULL, main.gsub = "@",
             xleg = min(xvar), yleg = max(obj$y), xlim = range(xvar),
             ylim = range(obj$y), points = FALSE,  median = TRUE, pch =  15,
             cex = 0.5, col =  gray(0.7),
             colors = c("cm", "gray", "rainbow", "heat", "terrain", "topo"), ...)

### Arguments

`obj` | a fitted gamlss object from fitting a gamlss distribution
`xvar` | the unique explanatory variable
`cent` | a vector with elements the % centile values for which the centile curves have to be evaluated
`legend` | whether a legend is required in the plot or not, the default is `legent=TRUE`
`ylab` | the y-variable label
`xlab` | the x-variable label
`main` | the main title here as character. If NULL the default title "centile curves using NO" (or the relevant distributions name) is shown
`main.gsub` | if the `main.gsub` (with default "@") appears in the `main` title then it is substituted with the default title.
`xleg` | position of the legend in the x-axis
`yleg` | position of the legend in the y-axis
`xlim` | the limits of the x-axis
`ylim` | the limits of the y-axis
`save` | whether to save the sample percentages or not with default equal to `FALSE`. In this case the sample percentages are printed but are not saved
`plot` | whether to plot the centiles. This option is useful for `centile.split`
`pch` | the character to be used as the default in plotting points see `par`
`cex` | size of character see `par`
`col` | plotting colour see `par`
`col.centiles` | Plotting colours for the centile curves
`lty.centiles` | line type for the centile curves
`lwd.centiles` | The line width for the centile curves
`colors` | the different colour schemes to be used for the fan-chart. The following are available `c("cm","gray", "rainbow", "heat", "terrain", "topo")`,
`points` | whether the data points should be plotted, default is `TRUE` for `centiles()` and `FALSE` for `centiles.fan()`
`median` | whether the median should be plotted (only in `centiles.fan()`)
`...` | for extra arguments

### Details

Centiles are calculated using the fitted values in `obj` and `xvar` must correspond exactly to the predictor in `obj` to plot correctly.

`col.centiles`, `lty.centiles` and `lwd.centiles` may be vector arguments and are recycled to the length `cent` if necessary.

### Value

A centile plot is produced and the sample centiles below each centile curve are printed (or saved)

### Warning

This function is appropriate only when one continuous explanatory variable is fitted in the model

### Author(s)

Mikis Stasinopoulos mikis.stasinopoulos@gamlss.org, Bob Rigby r.rigby@londonmet.ac.uk with contribution from Steve Ellison

### References

Rigby, R. A. and Stasinopoulos D. M. (2005). Generalized additive models for location, scale and shape,(with discussion), Appl. Statist., 54, part 3, pp 507-554.

Stasinopoulos D. M. Rigby R.A. (2007) Generalized additive models for location scale and shape (GAMLSS) in R. Journal of Statistical Software, Vol. 23, Issue 7, Dec 2007, http://www.jstatsoft.org/v23/i07.

Stasinopoulos D. M., Rigby R.A., Heller G., Voudouris V., and De Bastiani F., (2017) Flexible Regression and Smoothing: Using GAMLSS in R, Chapman and Hall/CRC.

(see also http://www.gamlss.org/).

### See Also

`gamlss`, `centiles.split` , `centiles.com`

### Examples

    data(abdom)
    h<-gamlss(y~pb(x), sigma.formula=~pb(x), family=BCT, data=abdom)
    # default plot
    centiles(h,xvar=abdom$x)
    # control of colours and lines
    centiles(h, xvar=abdom$x,  col.cent=c(2,3,4,5,1,5,4,3,2,1),
                  lwd.cent=c(1,1,1,1,2,1,1,1,1))
    #Control line types
    centiles(h, xvar=abdom$x,  col.cent=1, cent=c(.5,2.5,50,97.5,99.5),
                  lty.centiles=c(3,2,1,2,3),lwd.cent=c(1,1,2,1,1))
    # control of the main title
    centiles(h, xvar=abdom$x,  main="Abdominal data \n @")
    # the fan-chart
    centiles.fan(h,xvar=abdom$x, colors="rainbow")
    rm(h)

[Package gamlss version 5.0-2 Index]