Objective research and reviews to aid investing decisions
How much of a long-term total return advantage do investors perceive for high book-to-market (value) stocks over low book-to-market (growth) stocks? Is this perceived premium stable over time? In their April 2007 paper entitled "The Expected Value Premium", Long Chen, Ralitsa Petkova and Lu Zhang measure investor expectations for the value premium based on economic fundamentals rather than noisy historical returns. They assume that dividend growth rate equals capital gain rate over long periods, and that the top (bottom) 20% represents a high (low) the book-to-market ratio. Using monthly data for the period 1945-2005, they find that:
The following figure, taken from the paper, plots the premium expected by investors for stocks with the top 20% of book-to-market ratios relative to stocks with the bottom 20% of book-to-market ratios over the period 1945-2005. It shows that the expected value premium has been generally stable at about 6% over the past 60 years.

The next figure, also from the paper, shows the two components of this expected value premium: (1) the expected long-run dividend growth rate; and, (2) the expected dividend price ratio (yield). Note that dividend yield expectations peaked during a high-inflation subperiod, offsetting a decline in the expected dividend growth rate.

In summary, investors have expected a fairly stable value premium of about 6% per year over the past 60 years, derived mostly from growth in dividends.
For related research, see Blog Synthesis: The Value Premium.