Methodology

Methodology: The paper uses historical returns from 1871-2004 to assess the President's personal accounts proposal. It does 91 different simulations for a worker born in 1990 assuming that he or she experiences the actual returns from 1871-1914, 1872-1915, 1873-1916, all the way through 1961-2004. This sample has an average real stock market return of 6.8% annually, slightly above the 6.5% annual return assumed by the Social Security actuaries.

These historical returns are not, however, a good guide to future returns. The United States economy and stock market performed extremely well over the last century. Many factors suggest this lucky experience is not likely to be repeated: most analysts project slower GDP growth in the next century, the risk premium required for investing in equities may have diminished, and the P-E ratio is very high by historical standards.

The Wall Street Journal recently surveyed 10 leading financial economists, the median projection for the stock market real rate of return in this survey was 4.6% above inflation. This is slightly lower than the median real return of 4.8% in 15 countries from 1900-2000 surveyed by Dimson et al.

As a result, the paper also use "adjusted" stock market returns designed to match the median stock return