R: Plots centile curves split by x for a GAMLSS object

centiles.split {gamlss} | R Documentation

## Plots centile curves split by x for a GAMLSS object

### Description

This function plots centiles curves for separate ranges of the unique explanatory variable x. It is similar to the `centiles` function but the range of x is split at a user defined values `xcut.point` into r separate ranges. The functions also tabulates the sample percentages below each centile curve for each of the r ranges of x (for comparison with the model percentage given by cent) The model should have only one explanatory variable.

### Usage

    centiles.split(obj, xvar = NULL, xcut.points = NULL, n.inter = 4,
                   cent = c(0.4, 2, 10, 25, 50, 75, 90, 98, 99.6),
                   legend = FALSE, main = NULL, main.gsub = "@",
                   ylab = "y", xlab = "x", ylim = NULL, overlap = 0,
                   save = TRUE, plot = TRUE, ...)

### Arguments

`obj` | a fitted gamlss object from fitting a gamlss continuous distribution
`xvar` | the unique explanatory variable
`xcut.points` | the x-axis cut off points e.g. `c(20,30)`. If `xcut.points=NULL` then the `n.inter` argument is activated
`n.inter` | if `xcut.points=NULL` this argument gives the number of intervals in which the x-variable will be splited, with default 4
`cent` | a vector with elements the % centile values for which the centile curves are to be evaluated
`legend` | whether a legend is required in the plots or not, the default is `legent=FALSE`
`main` | the main title as character. If NULL the default title (shown the intervals) is shown
`main.gsub` | if the `main.gsub` (with default "@") appears in the `main` title then it is substituted with the default title.
`ylab` | the y-variable label
`xlab` | the x-variable label
`ylim` | the range of the y-variable axis
`overlap` | how much overlapping in the `xvar` intervals. Default value is `overlap=0` for non overlapping intervals
`save` | whether to save the sample percentages or not with default equal to `TRUE`. In this case the functions produce a matrix giving the sample percentages for each interval
`plot` | whether to plot the centles. This option is usefull if the sample statistics only are to be used
`...` | for extra arguments

### Value

Centile plots are produced and the sample centiles below each centile curve for each of the r ranges of x can be saved into a matrix.

### Warning

This function is appropriate when only 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 contributions from Elaine Borghie

### 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`, `centiles.com`

### Examples

    data(abdom)
    h<-gamlss(y~pb(x), sigma.formula=~pb(x), family=BCT, data=abdom)
    mout <- centiles.split(h,xvar=abdom$x)
    mout
    rm(h,mout)

[Package gamlss version 5.0-2 Index]