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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: How to find the best transformation for each variable in 120 periods |

Date |
Fri, 22 Feb 2013 17:55:03 +0000 |

Closer to home in a couple of senses are cube roots: http://www.stata-journal.com/article.html?article=st0223 Odd integer roots are equally well defined for arguments of any sign, although you have to go in Stata (e.g.) sign(x) * (abs(x))^(1/3) I've been working with glacier advance and retreat rates. Occasionally glaciers advance a lot or retreat a lot but most values are much closer to zero, so cube roots are a non-standard but useful way to plot them. Haven't tried regressions, as that is not the nature of the problem. Nick On Fri, Feb 22, 2013 at 5:28 PM, JVerkuilen (Gmail) <jvverkuilen@gmail.com> wrote: > On Fri, Feb 22, 2013 at 10:40 AM, Xixi Lin <winnielxx@gmail.com> wrote: >> Hi JVerkuilen, >> >> You are right that the key assumption is Gaussian errors, but my data >> does not have Gaussian errors, and I wanna use t statistics, so I >> wanna to fix the non-normal residuals by transforming the variables (I >> don't know what else to do to fix the Gaussian errors). Is there any >> better way to deal with it? Or Is there any papers that I can read >> about it? > > Well as I said, the Atkinson book is excellent. What's the nature of > the non-normality? Outliers? Are they symmetric? You can't really > decide this without thinking of what the likely problems are. > > The inverse hyperbolic sine is an under-used transformation for > long-tailed data with zero or negative values. It was originally part > of the Johnson system of distributions, which are based on > transformations of the Gaussian. It behaves like the log for large > magnitudes and like the square root for smaller ones. > > Burbidge, John B., Lonnie Magee and A. Leslie Robb. 1988 "Alternative > Transformations to Handle Extreme Values of the Dependent Variable." > Journal of the American Statistical Association, vol. 83, 123-127. > > http://worthwhile.typepad.com/worthwhile_canadian_initi/2011/07/a-rant-on-inverse-hyperbolic-sine-transformations.html * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**References**:**st: How to find the best transformation for each variable in 120 periods***From:*Xixi Lin <winnielxx@gmail.com>

**Re: st: How to find the best transformation for each variable in 120 periods***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

**Re: st: How to find the best transformation for each variable in 120 periods***From:*Xixi Lin <winnielxx@gmail.com>

**Re: st: How to find the best transformation for each variable in 120 periods***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

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