Tag Archives: statistics

Powerball Probability

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If you win the Powerball jackpot today, there are a few things you should know. After beating the 1 in 175 million odds, you have an 11 in 175 million chance of being killed in your car after collecting the winnings. If you survive that, you have a 327,250 to 175 million chance of being robbed of those winnings, and a 805,000 to 175 million chance that new mansion will go up in flames, according to Eve Waltermaurer, associate professor of sociology at State University of New York at New Paltz.

Probability is a bitch some times. (From the Poughkeepsie Journal)

How to manufacture facts like a champ

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“Boomerang kids: 85% of college grads move home,” blared a headline on CNNMoney.com. “85% of college grads return to nest,” echoed the New York Post. “Survey: 85% of New College Grads Move Back in with Mom and Dad,”said Time magazine’s website.

Recently, the 85 percent figure emerged in the presidential campaign, in an ad from the Republican group American Crossroads that blames President Barack Obama for the boomerang.

We rated the claim False, but as we dug into the number, we found the media had repeated it with little scrutiny. Journalists were content to copy a number from other news reports without verifying it — or even asking when the survey was conducted.

If the reporters had looked deeper, they would have found some oddities about the firm that claimed to have conducted the survey, a Philadelphia-area company called Twentysomething. The company’s website had an impressive list of staffers, but when we checked on them, we found several who either didn’t work for the company or appeared to be fictional.

The whole story is even weirder than you might imagine, and cane be seen over at Politifact. Moral of the story, news without public citations is suspect.

With all the crap wikipedia gets on accuracy, they are quite good about creating a culture of “citation needed”. We need more of that.

 

Evolution has a speed limit

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From physorg, a statistical analysis of the velocity of evolution from the fossil record, looking for an upper limit:

Large evolutionary changes in body size take a very long time. A mouse-to-elephant size change would take at least 24 million generations based on the maximum speed of evolution in the fossil record, according to the work of Alistair Evans and co-authors. Becoming smaller can happen much faster than becoming bigger: the evolution of pygmy elephants took 10 times fewer generations than the equivalent sheep-to-elephant size change.

Now that computational cycles are becoming cheaper, some really interesting statistical analysis can be done in science to ask questions we never could before. Very cool.

Freakonomics off the rails

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Great post at American Scientist about how Freakonomics has gone off the rails.

In our analysis of the Freakonomics approach, we encountered a range of avoidable mistakes, from back-of-the-envelope analyses gone wrong to unexamined assumptions to an uncritical reliance on the work of Levitt’s friends and colleagues. This turns accessibility on its head: Readers must work to discern which conclusions are fully quantitative, which are somewhat data driven and which are purely speculative.

I loved their first book, but as the author says, the strongest part was around Levitt’s own peer reviewed research. As they’ve gotten further away from that over the years, the methodology has become a lot more hear say and writing to a deadline.

The Seeds of Psychohistory?

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Isaac Asimov’s Foundation series was based on the idea that in the future overall societal events, like the rise and fall of governments, could be modeled mathematically.

Folks at the New England Complex Systems Institute have proposed a paper that looks at global food prices as compared to food riots and unrest, which in many cases directly preceeded much larger overthrows of governments. It’s a really interesting read.

This is not yet peer-reviewed published, so take that with the appropriate caution. The paper makes a point about the fact that many countries no longer have much of a local food system, which means they are directly impacted by global food price index. Two major statistical factors in the rise of global food prices are cited as commodity speculators and US corn ethanol policy.

I encourage interested people to read the whole paper, available on arXiv.