To be more precise:
1/2 = ((Pts in games 12-22) - (Pts in games 1-11)) / 22
Team 12-22 1-11 Pts Dif 1/2
Brown 5 8 -3 -.136
Clarkson 20 16 4 .182
Colgate 13 13 0 .000
Cornell 8 13 -5 -.227
Dartmouth 7 7 0 .000
Harvard 13 5 8 .364
Princeton 10 17 -7 -.318
RPI 11 17 -6 -.273
SLU 16 17 -1 -.045
Union 1 3 -2 -.091
Vermont 9 7 2 .091
Yale 15 11 4 .182