The Stanford study uses what's called a "risk-free" 4.14% discount rate, which is tied to 10-year Treasury bonds. The Government Accounting Standards Board requires corporate pensions to use a risk-free rate, but it allows public pension funds to discount pension liabilities at their expected rate of return, which the pension funds determine. Calstrs assumes a rate of return of 8%, Calpers 7.75% and the UC fund 7.5%. But the CEO of the global investment management firm BlackRock Inc., Laurence Fink, says Calpers would be lucky to earn 6% on its portfolio. A 5% return is more realistic. 

Using these higher return rates for their pension portfolios, the pension giants calculate a much smaller, but still significant, $55 billion shortfall. Discounting liabilities at these higher rates, however, ignores the probability that actual returns will fall below expected levels and allows pension funds to paper over the magnitude of their problem. The entire Wall Street Journal Article is here.