Posts filed under “Mathematics”

Self-Description, Black & White Edition



Category: Humor, Mathematics

QOTD: On Bias, Correlation and Objectivity

I love the way this unfolds: Someone did a study — I have no idea if its serious or not –  that suggested eating more chocolate improves a nation’s chances of producing Nobel Prize winners. One of the Nobel prize winners responded with the appropriate amount of snark: “Eric Cornell, who won the Nobel Prize…Read More

Category: Humor, Mathematics, Psychology, UnScience

Mandelbrot: Fractals, Chaos and Other Mathematical Visions

Source: Scientific American

Category: Mathematics, Science, Video

Defining Risk Versus Uncertainty

Longtime readers will recall that I find the Uncertainty meme to be mostly silly (see this and this). The foolishness continues to come up amongst allegedly serious people. I find many of these folks (mostly) devoid of original thought, choosing instead to repeat things pundits of questionable insight have previously said (PoQI™ is a registered trademark…Read More

Category: Mathematics, Philosophy, Really, really bad calls

The Dangers of Non-Modeled Narrative Story Tellers

  “He can take a model and turn it into a narrative”   Right after the election, Felix wrote a post “When quants tell stories.” Clever as it was, I had issues with the underlying premise – namely, that the value of Nate Silver’s modeling lay more in the narrative tale as told by Silver…Read More

Category: Investing, Mathematics, Philosophy, Politics, Quantitative, Really, really bad calls

No, Small Probabilities Are Not “Attractive to Sell”: A Comment

Category: Mathematics, Think Tank

Black Friday Skepticism (Finally!) Goes Mainstream

Over the years, I have been rather annoyed (perhaps too much) at the annual foolishness over Black Friday forecasts. Each year, we hear breathless predictions of ridiculous increases in consumer spending — holiday shopping rises 16% this season! — which turn out to be wildly over-optimistic, and are never confirmed by the actual data.

I’ve blogged about this annually for the past decade. Carl Bialik, the WSJ’s numbers guy, did a great piece on this a few years ago (Holiday Sales Numbers Don’t Add Up) but other than that, there is not alot of MSM recognition of the issue. I finally wrote it up for the Washington Post last year: Did Black Friday save the season? Beware the retail hype.

This year, the idea seems to have spread into the mainstream: Lots of coverage about it, with a few choice quotes from you know who tossed in for good measure.

Here is the The Globe and Mail:

“Barry Ritholtz, chief executive officer of Fusion IQ, a New York investment tool firm, is a long-time skeptic of early survey results. Not only are they released too early to compare to actual sales numbers, he says, but their measurement techniques are simply too indirect.

Foot-traffic assessments don’t properly separate browsers from buyers, Mr. Ritholz said. And he’s even more critical of surveys asking shoppers how much they plan to spend – which is how the NRF produces parts of its results. “Humans are terrible at forecasting their own behaviours,” he said.”

And NBC:

“Barry Ritholtz, director of equity research at Fusion IQ, takes to his popular blog every year to bemoan the “wildly optimistic” surveys that the media quotes at the end of Black Friday weekend.

Without fail, he says, the reports exaggerate consumer enthusiasm. He pointed to last year’s National Retail Foundation’s claim that sales had spiked by 16 percent – which, if true, would have been a record-breaking sum. There was no apparent attempt to check the data later on, but economists generally agree that consumer spending increased by less than 6 percent over the entire 2011 holiday season . . .

“You should be reluctant to draw too big a conclusion from one day,” Ritholtz said. “As we’ve seen, it never lives up to the hype. In fact, part of the reason there’s so much hype and false signals is there are so many people trying to get a read into that one day, far more than what you should typically be willing to see in one day. This is an economy, not an event.”

And MoneyWatch:

“As financial pundit Barry Ritholtz wrote last year: No, retail sales did not climb 16 percent. Surveys where people forecast their own future spending are, as we have seen repeatedly in the past, pretty much worthless. We actually have no idea just yet as to whether, and exactly how much, sales climbed. The data simply is not in yet. The most you can accurately say is according to some foot traffic measurements, more people appeared to be in stores on Black Friday 2011 than in 2010.”

So the good news is that print media has figured this out. Now, let’s see if television and radio can get their story straight . . .


Did Black Friday save the season? Beware the retail hype. (Washington Post, December 4, 2011)

Retail Sales Disappoint on False Black Friday Reports (December 13th, 2011)

No, Black Friday Sales Were Not Up 16% (not even 6%)   (November 28th, 2011)

Entering the Holiday Shopping Season (Beware Surveys!)   (October 28th, 2009)

Spinning Black Friday Retail Sales   (December 1st, 2008)

Repeat After Me: Spending Surveys Are Meaningless (October 2007)

More Bad Data from the NRF? (November 2006)

Holiday Sales Numbers Don’t Add Up (December 1st, 2005)


Don’t look to Black Friday for clues to the market
The Globe and Mail Thursday, Nov. 22 2012

Despite Hype, Black Friday Can’t Predict Holiday Shopping Patterns
Jon Schuppe
NBC, Nov 21, 2012

Lies, damned lies and Black Friday sales
Constantine von Hoffman
MoneyWatch, November 21, 2012


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Category: Consumer Spending, Data Analysis, Mathematics, Media, Really, really bad calls

Number Line

XKCD   I have just enough math background to a) appreciate this comic; b) hurt myself.    

Category: Humor, Mathematics, Weekend

Nate Silver and the Lessons of 2012

1. Breakout Star Of The Election Season You don’t have to be running to win. You don’t have to be number one. Concentrate on being a member of the scene and surviving. 2. Paid His Dues We’re so used to here today, gone tomorrow. Young people thrust into the spotlight who then disappear. Rebecca Black…Read More

Category: Data Analysis, Mathematics, Politics

Fibonacci Hurricane (Sandy)

click for larger image Source: Vic LeFaber, Google+

Category: Current Affairs, Digital Media, Mathematics, Science