"Most state and local pensions, [Alicia Munnell] shows, have improved their investment practices and are more professionally managed today than they were in the 1970s. Second, Munnell argues that variation in pension-plan funding is 'simply a story of fiscal discipline.' She claims that neither the 8 percent discount rate -- the assumed rate of return on investments that determines contributions and liabilities -- nor public employee unions' collective bargaining activities has caused the underfunding crisis."