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jennyli
Level I

Details about robust standard deviation from "Distribution" module?

The JMP documents guide me to the book by Huber & Ronchetti (2009). But it's still not clear for me how to calculate the robust standard deviation.

Thanks!

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vkessler
Level IV

Re: Details about robust standard deviation from "Distribution" module?

I´m also a bit puzzeld about the robust Standard Deviation in the Distribution Platform.

As far as i´m concerned, the robust standard deviation is someting like IQR/1.35. This is certainly not the case here:

 

JMP StdDev.png Can someone explain to me, how 2E19 should be robust, if IQR is 8E-12 and median is 2E-10??

 

Thanks!

 

 

 

 

 

 

 

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Re: Details about robust standard deviation from "Distribution" module?

JMP employs the same method as RobustReg which is part of SAS.  Details can be found in the RobustReg documentation in the section titled "Algorithm".

https://support.sas.com/documentation/onlinedoc/stat/142/rreg.pdf

This is page 8184 in the upper left corner and page 42 in the PDF document.

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vkessler
Level IV

Re: Details about robust standard deviation from "Distribution" module?

Thanks for the clarification.

However, I will stick to to the simple IQR/1.35 calculation, since the RobustReg procedure may return misleading results, if there are extreme outliers. That is at least the case for our data sets.

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