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Re: st: ladder question for right-skewed variable
From
David Hoaglin <[email protected]>
To
[email protected]
Subject
Re: st: ladder question for right-skewed variable
Date
Thu, 25 Apr 2013 20:44:58 -0400
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
<[email protected]> 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.
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