September 2, 2005

Obsessing Over Numbers

By PIPER FOGG

The budding economist Benjamin A. Olken sees life as one big puzzle to solve.

For instance, at a Seder a few years ago, Mr. Olken set out to test whether a Passover story his father had told was correct. According to the story, there were initially only 70 Jews in Egypt, but 400 years later, at the time of Exodus, there were 600,000.

Was that growth rate reasonable, he wanted to know, or did the Bible get it wrong? His family waited while he worked it out. Mr. Olken says that he