Market Efficiency Revisited

When you unravel all of the puffery, investors either believe that the market is efficient or they do not. Of course in the short term it is very messy and very noisy. Perhaps this is really the wrong question. Even if you believe that the market is not efficient what is the cost of seeking to exploit the perceived inefficiency? In reality , very, very few will manage to outpace the market on a cost and risk adjusted basis.