No.	Name	Spring 2005 R2	Spring 2005 Parameters	Spring 2006 R2	Spring 2006 Parameters	R2 of Predicted 2006 Values by 2005 Model	Over-/Under-Prediction of True Benefits
1	Delay polynomial	0.60	β1 1.16, β2 − .15, β3 .01, β4−, β5−	0.60	β1 .73, β2−, β3−, β4 0.14, β5 − .035	0.57	-1%
2	Delay log-linear	0.59	β1 .36, β2 .88, β3 .027	0.59	β1 .51, β2 .37, β3 − .041	0.57	-3%
3	Distance-normalized linear	0.52	β1 .45	0.46	β1 .49	0.39	-19%
4	Time & delay log-log	0.48	β1 1.07, β2 .52, β3 − .15	0.53	β1 1.06, β2 .49, β3 − .18	0.56	17%
5	Linear	0.39	β1 .35	0.25	β1 .25	0.17	51%
6	Distance-normalized log-log	0.35	β1 1.79	0.42	β1 1.81	0.46	27%
7	Square root linear	0.34	β1 1.36	0.22	β1 0.92	0.12	62%
8	Time-normalized log-log	>0.33	β1 1.30, β2 − .14	0.24	β1 1.60, β2 − .13	0.43	7%
9	Log-log	0.26	β1 1.06	0.12	β1 0.90	0.24	95%