Owners Hold Off On Sales Of Homes:

Traditionally, home ownership has been about trading up. People bought a starter house and lived there for a while. Then, as their families grew or their incomes rose, they moved to a bigger house or a tonier neighborhood. But the hot local real estate market is disrupting that pattern.

This is a fascinating (and long) article. The link above requires a somewhat onerous registration, but Bugmenot to the rescue!