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From |
Gabriel Nelson <lgabrielnelson@gmail.com> |

To |
statalist <statalist@hsphsun2.harvard.edu> |

Subject |
Re: st: ladder question for right-skewed variable |

Date |
Fri, 26 Apr 2013 10:41:18 -0700 |

Thanks for the help David. Any idea why the ladder command would fail to suggest transformations? I can see that the variable needs to be transformed, and the variable does not show a bimodal structure. I am worried that since the ladder command fails to run, there is some other problem going on with the variable. By the way, the variable measures the amount of people that report being displaced by violence by municipality in Colombia. Thank you, Gabriel On Thu, Apr 25, 2013 at 5:44 PM, David Hoaglin <dchoaglin@gmail.com> wrote: > > Gabriel, > > The ratio of the largest value to the smallest value is quite large, > so a transformation is likely to be useful. As a first step ("first > aid"), I suggest that you try the logarithm (base 10). > > Usually the context of the data plays a role in the choice of a > transformation, so that the result is meaningful. What is the nature > of disp_2000? > > With 1010 observations you should check whether the data has some > structure (e.g., two or more modes or groups), for example, by making > a histogram with a sizable number of bins (say 25 or so). If you find > structure, you will need to deal with that also. > > David Hoaglin > > On Thu, Apr 25, 2013 at 8:11 PM, Gabriel Nelson > <lgabrielnelson@gmail.com> wrote: > > I have a variable that is right-skewed. I used the the ladder command > > to see suggested transformations. However, no transformations appeared > > in the output. I'm guessing that this does not mean the raw form is > > better, because there is an option for 'raw' on this list. > > > > Here is the output for the sum, detail command for the variable: > > > > > > > > sum disp_2000, detail > > > > Number displaced 2000 (if data unavailable go up > > to 2003 > > ------------------------------------------------------------- > > > > Percentiles Smallest > > 1% 1 1 > > 5% 2 1 > > 10% 3 1 Obs 1010 > > 25% 6 1 Sum of Wgt. 1010 > > > > > > 50% 15.5 Mean 281.5297 > > Largest Std. Dev. 1217.168 > > 75% 82 9421 > > 90% 436.5 9505 Variance 1481497 > > > > 95% 1251 16255 Skewness 9.012044 > > 99% 5953 19569 Kurtosis 108.8061 > > > > Any suggestions are greatly appreciated. > * > * 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/ * * 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/

**Follow-Ups**:**Re: st: ladder question for right-skewed variable***From:*Nick Cox <njcoxstata@gmail.com>

**References**:**st: ladder question for right-skewed variable***From:*Gabriel Nelson <lgabrielnelson@gmail.com>

**Re: st: ladder question for right-skewed variable***From:*David Hoaglin <dchoaglin@gmail.com>

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