Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Library: stats
See also: twboxcox hinesplot boxcoxdens

Quantlet: boxcox
Description: computes the Box-Cox transformation of x

Usage: y = boxcox (x, p)
Input:
x n x q
p scalar
Output:
y n x q transformed data

Example:

; loads the library stats

library("stats")   

; loads the library graphic

library("graphic")   

; reset random generator 

randomize(0)

; generate x (skewed)

x = 0.05+0.9.*uniform (250)

x = qfc (x, 2)

; create a display

t = createdisplay(1,2)

; show a qq-plot of x

xp = grqqn(x)

show (t, 1, 1, xp)

; now transform with boxcox (p=0)

y = boxcox(x, 0)

; show a qq-plot of y

yp = grqqn(y)

show (t, 1, 2, yp) 

Result:

shows first a qq plot with the original data. The data are

skewed. The second plot shows a qq-plot with the

transformed data. The data are less skewed now and the

distribution looks more normal. 


Library: stats
See also: twboxcox hinesplot boxcoxdens

Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Author: Michaela Dranganska, Ulrich Dorazelski, 951002, Susanne Hannappel, 970220 Sigbert Klinke, 970820
(C) MD*TECH Method and Data Technologies, 21.9.2000