Tuesday, January 14, 2014

The Oak Island Mystery Show...and Statistics

The History Channel has taken a break from Hitler and Pawn shows to have a series on the Oak Island Mystery, specifically "The Money Pit". I remember reading about this pit as a child, and much like stories of the Loch Ness Monster and alien spaceships, there haven't been any real breakthroughs in the last 40ish years.

The short discussion is the Money Pit is this mysterious pit that supposedly has treasure in the bottom of it. Nobody knows, of course, because supposedly booby traps were set, and and now it's flooded with salt water. There's a whole mythology around the pit, I won't bore any with the details...but they actually kinda-sorta found something, and had some statistics on the show.

One of the many stories about the island is a mysterious cache of coconut fiber that was supposedly on the island, years ago. The nearest coconut trees are a thousand miles away, so finding such fiber would be a sign that someone (or a really bad storm) brought coconut fiber (common on ships in the sailing vessel days, to stabilize cargoes) to the island.

Sure enough, they did some digging, and found some coconut fiber. A natural question, of course, is to date the fiber, to get an idea of when it might have been brought to the island. I used to teach carbon-14 dating in class, before admin told me it was too hard for students (a shame, since I learned it in 10th grade algebra...).

Anyway, they get it dated, and the dating lab said they were 95% confident that the fiber was from the 12th to the 14th century.

Hey, look, statistics! What they've just said here, is, using a technique that (according to theory) works 95% of the time, they're confident the fiber dates between 1200 and 1400 AD (that means a 100 year margin of error, and the sample mean likely dates to 1300 AD). That's a "confidence interval."

Now, the PROBABILITY that the true age of the coconut fiber is between 1200 and 1400 AD? That probability is 0 or 1...we'll never know. But the technique works 95% of the time, and that's good enough. Even if the technique didn't work, it's not outrageous to suppose the fiber is from 1199 or 1401 or something. Anyway, that's why they call it "confidence" as opposed to probability.

And it's kinda neat they finally found a tiny little bit of something that indicates that maybe that hole is quite old, indeed...at least if you want to make the leap to think that the hole is related to the coconut fiber.