Exhibit 4 - Impact of Standard Deviation on VOES cost Standard Standard Standard Standard deviation = 2.5 deviation = 2 |deviation = 1.5 deviation = 1 2.50 2.50 2.50 2.50 1.73 1.54 1 26 0.79 1.08 0.80 0.46 0.11 0.63 0.36 0.12 0.01 0.39 0.18 0.04 0.00 0.33 0.19 0.09 0.02 0.39 0.32 0.25 0.16 0.51 0.50 0.50 0.50 -8 0.66 0.69 0.75 0.84 0.79 0.84 0.91 0.98 -10 0.89 0.93 0.98 1.00 -11 0.95 0.98 1.00 1.00 -12 0.98 0.99 1.00 1.00 -13 0.99 1.00 1.00 1.00 -14 1.00 1.00 1.00 1.00 -15 1.00 1.00 1.00 1.00 -16 1.00 1.00 1.00 1.00