At the moment no one can prove that these Internet stocks are overpriced. But many of us have deep suspicions.

The median person still thought that their prices were going to go up. That’s the definition of a bubble.

There is no doubt that these are real people making real choices for high stakes, and we rarely get to observe such pure decisions.

There have been hundreds of papers on subjects from picking students for a school to predicting the survival of cancer patients.