Comparisons between projections for the three alternative scenarios (low-cost, intermediate, and high-cost) and the stochastic simulations presented in this report should be made with a full understanding of the limitations on these two approaches for illustrating uncertainty. The stochastic simulations include random annual variations in several key parameters, but these annual variations tend to cancel out over time so the average variation for each parameter diminishes with longer periods, approaching zero variation across the simulations. (See Actuarial Study 117 at
www.socialsecurity.gov/OACT/NOTES/s2000s.html for additional details.) For this and other reasons, the variation reflected in the stochastic simulations is unreasonably small. In addition, the variation across the three alternative scenarios was increased this year by reversing the assignment of ultimate price inflation assumptions between the low-cost and high-cost scenarios.