Wednesday, February 15, 2006

Cheney and Bayes

As you know, Dick Cheney has become the first U.S. vice-president after 201 years who has shot a person. Poor Harry Whittington, a 78-year-old Texas attorney and a supporter of the Bush-Cheney ticket, suffered a setback yesterday. As Prof. Charles M. has pointed out, the Los Angeles Times reports that
  • a hospital spokesman said the chances that "one problematic birdshot" would migrate as it has toward Whittington's heart are "one in 99.99."

What does the figure mean? Yes, it is another Bayesian probability estimate. But what the conjectured probability actually is? It is either

  • one in 100, i.e. 1 percent, expressed with a nonsensical accuracy
  • or one in 10,000 i.e. 0.01 percent (so that the complement has a 99.99% probability)

You can choose any answer you want - 1 percent or 0.01 percent - but the actual answer is that under the exact conditions of Mr. Whittington including the doctors and spokespersonnel who don't know things like math, the probability was unfortunately 100 percent...

Every blog interprets this story according to its ideology. This blog first of all wishes Mr. Whittington strong nerves and good luck to become fit once again (he has a strong heart), and second of all we use it as an example of the unscientific nature of most Bayesian estimates.