Brad Efron, Tornadoes, and Diane Sawyer

Brad Efron wrote to me and posed an interesting statistical question:

“Last Wednesday Diane Sawyer interviewed an Oklahoma woman who twice had had her home destroyed by a force-4 tornado. “A one in a hundred-trillion chance!” said Diane. ABC showed a nice map with the current storm’s track of destruction shaded in, about 18 miles long and 1 mile wide. Then the track of the 1999 storm was superimposed, about the same dimensions, the two intersecting in a roughly 1 square mile lozenge. Diane added that the woman “lives right in the center of Tornado alley.”

Question: what odds should have Diane quoted? (and for that matter, what is the right event to consider?)

Regards, Brad”

Anyone have a good answer?

By the way, I should add that Diane Sawyer has a history of broadcasting stories filled with numerical illiteracy. She did a long series opposing the use of lean finely textured beef (LFTB), also known as “pink slime.” In fact, LFTB is perfectly healthy, its use requires slaughtering many fewer cows each year and makes meat cheaper for poor people. The series was denounced by many scientists and even environmentalists. ABC is being sued for over one billion dollars.

She also did a long series on “Buy America” encouraging people to shun cheap goods from abroad. This is like telling people who live in Cleveland to shun buying any products and services not produced in Cleveland (including not watching ABC news which is produced in New York, or reading statistics papers not written in Cleveland.) This high-school level mistake in economics is another example of Ms. Sawyer’s numerical illiteracy.

But I digress.

Let’s return to Brad’s question:

What is a good way to compute the odds that someone has their house destroyed by a tornado twice?

I open it up for discussion.