Some are duds, in fact. The Beating the Dow method was to pick the lowest priced of the 10 highest yielders. That worked well. Our various Foolish Four strategies have refined that approach even further by eliminating the lowest priced high yielder because it was too often a stock in real trouble . The square root of price.
Beta is a measure of volatility.
A stock with a high beta tends to move more rapidly and to greater extremes than the market as a whole. Of course, beta is based on long-term averages, and no stock follows the rules exactly. Still, stocks with higher betas tend to be more lively, and stocks with betas lower than 1 tend to move more sluggishly. By selecting stocks with high yields, we are selecting stocks whose price movement is more likely to be up . Therefore, by selecting for high beta, the magnitude of the upward movement is increased.