I can't find a working link to the original Sklansky article from the Mag but here's the discussion thread re: 4th down play calling.
http://archiveserver.twoplustwo.com/...te_id/1#import
oh and here's an academic paper with lots of math and symbols and footnotes and citations and stuff. Paper by David Romer, UC-Berkeley.
http://emlab.berkeley.edu/users/drom...s/nber9024.pdf