Most people expect P/E to measure current valuation and to show historical patterns. But more features are available from some versions of P/E. The methodology behind the Crestmont P/E enables investors to anticipate the future. It may not precisely predict the market ten years away, but it frames within a relatively tight range the likely outcome. One component from determining the Crestmont P/E is a means to assess the future trend line for EPS using estimates of future economic growth (GDP).
The latest book from Martin Leibowitz, one of the most respected thinkers in the investment industry, attempts to justify the endowment model of investing. As Michael Edesess writes in this review, Leibowitz's defense is highly problematic, and that should concern any advisor utilizing a Yale-like strategy.