Sounds interesting, but I couldn't be bothered with signing up for scribd and all the other hoops I had to jump through to download the original PDF, so I googled for a link - here it is, I hope there's no problem with sharing it here:
http://www.hks.harvard.edu/presspol/...d39_powers.pdf
You can also search for it here:
http://www.hks.harvard.edu/presspol/publications/