ABSTRACT
Since the publication of a famous paper by Fama, economists have become increasingly interested in the dynamic efficiency of financial and other markets. Market efficiency is a simple implication of investor rationality: an obvious bargain will be in great demand, and this demand will drive its price up until the implied return no longer is abnormally high. Daily price observations would, perhaps, be ideal. However, the improvements in the results are not likely to be worth the considerable effort involved in obtaining daily quotes. Since the oil market has moved quickly at times, the observations should not be too far apart. Arabian light is important as the OPEC market price, and it would be interesting to investigate the discrepancy that existed for some time between the official prices of this and similar grades.
