- The long-term mean of the Shiller Cyclically Adjusted Price to Earnings Ratio P/E10 incorporates time-inconsistent data, causing substantial underprediction of realized stock returns in recent decades.
- Better prediction of market direction and returns can be achieved by using a 35-year moving-average of P/E10, instead of its long-term mean.
- Stocks seem only overvalued after P/E10 becomes greater than its 35-year moving average plus 7.5 added to it, with major market declines starting one to five years thereafter.
- An analysis shows that whenever P/E10 rose from below to above its 35-year moving average significant ten-year gains for stocks followed.
- Both the historic market trend, and the current level of the Shiller CAPE P/E10, suggest probable real market gains of about 20% to 28% to the end of 2020.