Black Friday Mathematics

Published by patrick honner on

I thought I’d do a little analytic research on Black Friday spending, so I punched up Wolfram Alpha to see what it could tell me.

Although W|A doesn’t seem to have economic data tied to the specific date, it shows that retail spending in the U.S. is about $386 billion per month, or around $13 billion per day.

A report from Businessweek claims that about $20 billion was spent last year on Black Friday.  This suggests that around $7 billion more is being spent today!

The increase may be even greater.  In its data, Wolfram Alpha includes spending in some categories (motor vehicle and parts dealers–$65.68 billion per month;  food and beverage stores–$51.65 billion per month) that might not be counted as “holiday spending.”   There may be a more targeted metric for measuring the success of Black Friday; researching, or creating, this measure could be a fun little project.

One nice little feature from Wolfram Alpha was the graph of consumer spending.  At the end of each calendar year, there is a sudden spike followed by a steep drop.  It’s not too hard to tell the accompanying story for that data!

Categories: Application

patrick honner

Math teacher in Brooklyn, New York


Andy Parkinson · November 25, 2011 at 10:47 am

I wonder how how would it look in a (Walter Shewhart) SPC control chart

MrHonner · November 26, 2011 at 9:43 am

I’m not familiar with how control charts work. What exactly would we be looking at in this case?

MrHonner · November 29, 2011 at 5:25 pm

This is pretty vague:

“A phenomenon will be said to be controlled when, through the use of past experience, we can predict, at least within limits, how the phenomenon may be expected to vary in the future.”

Is there a rigorous theory underlying this somewhere?

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