In a recent Journal of Corporate Finance article, the authors find that investors cannot consistently beat the market indexes by investing in a common stock, assuming all public (but not private) information had been absorbed into the market. According to the Efficient Market Hypothesis, does such a finding support the weak, semi-strong, or strong form of market efficiency? Also, why and how should society control for people making buy/sell decisions in the market if we assume a semi-string form of efficiency? What if the market were strong form efficient?