Sp. Kothari et J. Shanken, BOOK-TO-MARKET, DIVIDEND YIELD, AND EXPECTED MARKET RETURNS - A TIME-SERIES ANALYSIS, Journal of financial economics, 44(2), 1997, pp. 169-203
We find reliable evidence that both book-to-market (B/M) and dividend
yield track time-series variation in expected real stock returns over
the period 1926-91 (in which B/M is stronger) and the subperiod 1941-9
1 (in which dividend yield is stronger). A Bayesian bootstrap procedur
e implies that an investor with prior belief 0.5 that expected returns
on the equal-weighted index are never negative comes away from the fu
ll-period B/M evidence with posterior probability 0.08 for the hypothe
sis (0.14 with the impact of the 1933 outlier tempered). Although this
raises doubts about market efficiency, the post-1940 evidence is cons
istent with expected returns always being positive.