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Standard Deviation Demystified Using DAX

Anakin asked questions about Power Pivot's STDEVX.P

“Only a master of evil formulas, Darth!”
”…hmm, which kinda DOES make you the master doesn’t it?  Crap, I give up, just
chop me in half and get it over with, but make sure Luke sees you do it ok?”

Anakin’s Second Line of Questioning

Two weeks ago I posted about a particular student’s knack for making me learn new stuff, specifically the “bubble up ranks” method.  (Ooh, I forgot to circle back and cover the “bubble up exceptions” part – making a note of that now).

Anyway, he also pressed me to teach STDDEVX().  That’s a first.  “No worries,” I said, “it’s just another X function – but only you will know if the numbers are correct, because I don’t know what Standard Deviation truly means.”

Embarrassing isn’t it?  To be a numbers guy and not know what Standard Deviation means?  I was on the varsity calculus team in high school.  I even have a Math major (to go along with my Computer Science and Philosophy majors – jack of all trades, master of none).  How did I slip through the cracks on Standard Deviation?

OK yeah, it measures deviation, variability.  I get that from the name.  And yeah I even “learned” it in Statistics class in college, to the extent I ever showed up at 8 am.  But I didn’t grok it.  Didn’t breathe it in deeply.  Until now. 

It’s all fun and games until the Football Project Returns!

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