March 2008

Simulating Major League Baseball

Here is a neat application of simulation from this weekend's New York Times. The authors, a graduate student and professor at Cornell, simulated the entire history of Major League Baseball 10,000 times to see just how "mythic" Joe DiMaggio’s 56-game hitting streak really is. They find that 56-game streaks are not at all unusual, and furthermore that Joe DiMaggio wasn't even the most likely to set the record!

How 0.05 comes into rule?

Recently I read an article written by Erin Leahey, talking about how the usage of statistical significance testing, the 0.05 cut-off value and the three-star system becomes legitimized and dominant in mainstream sociology. According to Erin, one star stands for p<=.05, two stars p<=.01 and three stars p<=.001. But I feel the cut-off values are something like .01, .05 and .10 respectively. Anyway, Erin attributed the first usage of .05 significance level to R. A. Fisher’s book, Design of Experiments in 1935.

Does Medicare Save Lives?

A few weeks ago I attended a talk by David Card, a Berkeley economist currently on leave here at Harvard. Card's talk was on a new paper, written with Carlos Dobkin and Nicole Maestos, entitled "Does Medicare Save Lives?"

In the paper, Card and his coauthors analyze data on over 400,000 hospital emergency room encounters in California for "non-deferrable" admissions, which are defined as conditions for which daily admissions rates do not differ during the week.

Primary Crosstabs

We're lucky to have two contested Presidential primaries. One of my favorite habits is to look at cross-tabs of candidate preferences by party and county. Here's an example of an Iowa cross-tab, showing the number of Iowa counties by Republican winner and Democratic winner: