Category Archives: Math! Urk!

July 15, 2013, 7:55 pm

Today in Bad Math: Military and Sexual Assault Division

Lindsay Rodman, a Marine officer (and, we are told, a Harvard and Duke graduate), attempts to unskew the numbers on sexual assaults in the military in the Wall Street Journal. “The Pentagon’s Bad Math on Sexual Assault” starts by saying that:

In the days since the Defense Department’s May 7 release of its 2012 Annual Report on Sexual Assault in the Military, the media and lawmakers have been abuzz. The report’s estimate that last year 26,000 service members experienced unwanted sexual contact prompted many to conclude, incorrectly, that this reliably estimated the number of victims of sexual assault. The 2012 estimate was also significantly higher than the last estimate, causing some to proclaim a growing “epidemic” of sexual assault in the military. The truth is that the 26,000 figure is such bad math—derived from an unscientific sample set and extrapolated military-wide—that no …

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May 6, 2013, 2:35 pm

Today In Statistical Silliness

Heck, since I’m on that topic, I’ll pick on the New York Times.

Now comes the hard part: Can movie studios, mired in a steep box-office slump, keep the momentum going?

Between the first weekend in May and Labor Day, a period that typically accounts for 40 percent of annual movie ticket sales, Hollywood rapidly parades its biggest floats — loud, visual-effects-laden behemoths like the coming “Man of Steel” and “Lone Ranger” that cost $200 million (or more) to make and $150 million to market globally.

I note that May to September is a four-month stretch, i.e. roughly 33% of the year. Getting 40% of revenue in 33% of the year hardly strikes me as hugely disproportionate. Certainly, it’s substantial, but not really worthy of the “tent-pole” treatment that summer gets in the movie industry, yet the Times reports the figure breathlessly and with grave import.

May 3, 2013, 8:13 pm

This Week In Statistical Silliness

The Cato Institute discovers that – during hard times – the government spends more.

Being the Cato Institute however, that’s not interesting, so they spin it around. More government spending leads to lower GDP:

Higher government spending growth in a year corresponds to reduced private GDP growth that year. For example, if real government spending growth was zero, private GDP would be expected to grow at 4.2 percent. If real government spending growth was 5 percent, private GDP growth would be expected to fall to 2.8 percent.


What’s really happening, of course, is that during recessions, government spending goes up because of unemployment insurance and welfare programs in general get more (unfortunately) customers. It’s not that government spending knocks down private GDP, it’s that …

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