The answer to why gas prices go up and (more rarely these days) down may be here in the numbers, in five quantitative studies undertaken by Professor MacAvoy and several graduate students at the Yale U. School of Management and Economics. Their studies quantify factors of supply and regulation at three levels of industry activity, applying econometrics to studies of regional markets for gas transmission services, competition among the few in the natural gas pipelines industry after partial deregulation, the basis differentials as a measure of performance in partially deregulated pipeline transportation markets, probability of natural gas storage resulting from federal deregulation, and revision of the model of gas wellhead prices and quantities for deregulation. Annotation ©2008 Book News, Inc., Portland, OR (booknews.com)