gamlss (version 4.2-4)

histDist: This function plots the histogram and a fitted (GAMLSS family) distribution to a variable

Description

This function fits constants to the parameters of a GAMLSS family distribution and them plot the histogram and the fitted distribution.

Usage

histDist(y, family = NO, freq = NULL, 
        density = FALSE, nbins = 10, xlim = NULL, 
        ylim = NULL, main = NULL, xlab = NULL, 
        ylab = NULL, data = NULL, ...)

Arguments

y

a vector for the response variable

family

a gamlss.family distribution

freq

the frequencies of the data in y if exist. freq is used as weights in the gamlss fit

density

default value is FALSE. Change to TRUE if you would like a non-parametric density plot together with the parametric fitted distribution plot (for continuous variable only)

nbins

The suggested number of bins (argument passed to truehist() of package MASS). Either a positive integer, or a character string naming a rule: "Scott" or "Freedman-Diaconis" or "FD". (Case is ignored.)

xlim

the minimum and the maximum x-axis value (if the default values are out of range)

ylim

the minimum and the maximum y-axis value (if the default values are out of range)

main

the main title for the plot

xlab

the label in the x-axis

ylab

the label in the y-axis

data

the data.frame

...

for extra arguments to be passed to the gamlss function

Value

• returns a plot

Details

This function first fits constants for each parameters of a GAMLSS distribution family using the gamlss function and them plots the fitted distribution together with the appropriate plot according to whether the y variable is of a continuous or discrete type. Histogram is plotted for continuous and barplot for discrete variables. The function truehist of Venables and Ripley's MASS package is used for the histogram plotting.

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. and Akantziliotou C. (2006) Instructions on how to use the GAMLSS package in R. Accompanying documentation in the current GAMLSS help files, (see also http://www.gamlss.org/).

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.

See Also

gamlss, gamlss.family

Examples

data(abdom)
histDist(y,family="NO", data=abdom)
# use the ylim 
histDist(y,family="NO", ylim=c(0,0.005), data=abdom)
# bad fit use PE
histDist(y,family="PE",ymax=0.005, data=abdom)
# discere data counts 
#  Hand at al. p150  Leptinotarsa decemlineata
y <- c(0,1,2,3,4,6,7,8,10,11)
freq <- c(33,12,5,6,5,2,2,2,1,2) 
histDist(y, "NBI", freq=freq)
# the same as 
histDist(rep(y,freq), "NBI")