Box-Cox Transforms
Computes the Box-Cox transform of the data for a given value of lambda. Includes the scaling factor.
bct(y, lambda)
y |
Vector of data to be transformed. |
lambda |
Scalar exponent for transform (1 is linear, 0 is log). |
bct computes the Box-Cox family of transforms: y = (y\^lambda -
1)/(lambda*gm\^(lambda-1)), where gm is the geometric mean of the y's.
returns log(y)*gm when lambda equals 0.
A vector of the same length as y with the corresponding transformed values.
Greg Snow 538280@gmail.com
vis.boxcox, vis.boxcoxu,
boxcox in package MASS, other implementations in various
packages
y <- rlnorm(500, 3, 2) par(mfrow=c(2,2)) qqnorm(y) qqnorm(bct(y,1/2)) qqnorm(bct(y,0)) hist(bct(y,0))
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