I hope for their wives sakes the stopwatches skewed the results.This article demonstrates that subjective factors like sense of control, distress, and sexual satisfaction need to be considered when treating this highly prevalent disorder."
The researchers timed ejaculations by giving stopwatches to the sex partners of more than 1,500 men.
Writing in the Journal of Sexual Medicine, they said they were trying to set parameters for a condition that is poorly defined medically.
About 200 of the men in the study suffered from premature ejaculation, they found. A man with the condition took 1.8 minutes to ejaculate after beginning intercourse compared to 7.3 minutes for most of the men.

http://www.cnn.com/2005/HEALTH/conditions/04/14/health.ejaculation.reut/index.html