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How to calculate 3*sigma(Std Dev) in Analyze/Tabulate

Hi Friends

One of customer asked How to calculate 3*sigma(Std Dev) in Analyze/Tabulate.

And/or, Is there some method that we could place 3*sigma(Std Dev) in default statistics like std dev.

 

You could refer attached (maybe, made by Brady)

 

Thanks

Re: How to calculate 3*sigma(Std Dev) in Analyze/Tabulate

Hello Ikju,

 

For the record, I do not like the solution I am about to propose. It does, however, provide the desired statistic, and is the only way I can think of to do so, using Tabulate.

 

It uses the fact that stdev(3x) = 3stdv(x)

 

So, in tabulate, make a right-click transform column of the column whose stddev you want. Select a formula transform, and for the formula, simply multiply the original column(s) by 3.

 

Then, when the standard deviation of this new column is computed, it will actually be 3 times the standard deviation of the original column, which is what is desired.

 

 

Re: How to calculate 3*sigma(Std Dev) in Analyze/TabulateHi Brady,
This is roundabout but very simple, clear method.
I wonder why I couldn't think stdev(3x) = 3stdev(x)
ThanksRe: How to calculate 3*sigma(Std Dev) in Analyze/Tabulate

Hi IkJu,

Not a direct answer to your question but I use the control chart platform to get my 3 sigma because I feel the visualization of the spread over time is a valuable addition to the raw number.

 

Lou

Re: How to calculate 3*sigma(Std Dev) in Analyze/TabulateHi Lou,
I'm also going to recommend 'using control chart'.
Thank you