不知道是不是下面的这个命令
Title
[R] lnskew0 -- Find zero-skewness log or Box-Cox transform
Syntax
Zero-skewness log transform
lnskew0 newvar = exp [if] [in] [, options]
Zero-skewness Box-Cox transform
bcskew0 newvar = exp [if] [in] [, options]
options Description
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Main
delta(#) increment for derivative of skewness function; default is delta(0.02) for
lnskew0 and delta(0.01) for bcskew0
zero(#) value for determining convergence; default is zero(0.001)
level(#) set confidence level; default is level(95)
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Menu
lnskew0
Data > Create or change data > Other variable-creation commands > Zero-skewness log
transform
bcskew0
Data > Create or change data > Other variable-creation commands > Box-Cox transform
Description
lnskew0 creates newvar = ln(+/-exp - k), choosing k and the sign of exp so that the
skewness of newvar is zero.
bcskew0 creates newvar = (exp^L - 1)/L, the Box-Cox power transformation (Box and Cox
1964), choosing L so that the skewness of newvar is zero. exp must be strictly positive.
Also see [R] boxcox for maximum likelihood estimation of L.
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