centiles.split: Plots centile curves split by x for a GAMLSS object

In gamlss: Generalized Additive Models for Location Scale and Shape

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, 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 split, 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 useful 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, Bob Rigby 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.

Rigby, R. A., Stasinopoulos, D. M., Heller, G. Z., and De Bastiani, F. (2019) Distributions for modeling location, scale, and shape: Using GAMLSS in R, Chapman and Hall/CRC. An older version can be found in https://www.gamlss.com/.

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, https://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 https://www.gamlss.com/).

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)

gamlss documentation built on May 29, 2024, 6:08 a.m.