Advent of Code is back! Unwrap daily challenges to sharpen your Alteryx skills and earn badges along the way! Learn more now.

Alteryx Designer Desktop Discussions

Find answers, ask questions, and share expertise about Alteryx Designer Desktop and Intelligence Suite.
SOLVED

Calculate StdDev for populations vs. samples

mbogusz
9 - Comet

When calculating the StdDev with the Summarize tool, what is the cutoff between when Alteryx uses the StdDev of a population formula vs. the StdDev of a sample formula?  How does it know?  I am wondering because Excel explicitly allows users to choose STDEV.P or STDEV.S and is there a way to have Alteryx calculate the equivalent of a STDEV.P on a sample as can be done in Excel with little finagling?

 

For example, for the below array, Alteryx is using the Summarize tool>StdDev for a sample formula and not population formula because it knows better, but what if I wanted it to use the population formula regardless of the sample size.

 

([100.1, 99.975, 100.1, 100.1])

 

STDEV.P: 0.054126588

clipboard_image_2.png

 

Alteryx StdDev (outputs the STDEV.S only because it knows better): 0.0625

clipboard_image_5.png

 

Population calc vs. sample calc variance: -0.008373412

 

StdDev of a population formula:

clipboard_image_6.png

 

StdDev of a sample formula:

clipboard_image_7.png

Works cited:

https://www.khanacademy.org/math/probability/data-distributions-a1/summarizing-spread-distributions/...

2 REPLIES 2
SamDesk
11 - Bolide

Hi @mbogusz 

 

The summarise tool StdDev is always the sample variant. To use the population StdDev, you can use a macro from the community that Alteryx has recommended to users.

 

Sam 🙂

mbogusz
9 - Comet

Thank you @SamDesk!  Genius!

Labels