Hypothesis testing based on goodness-of-fit in the moving average time series model

Small sample properties of t-tests are compared with those of tests based on relative goodness- of-fit in the context of the first order moving average time series model. Monte Carlo experiments reported in the paper suggest that the actual size of these t-tests greatly exceeds theoretical large sample significance levels, while conformity of goodness-of-fit statistics to the appropriate chi-square or F-distributions is much closer. The evidence presented suggests that practitioners are well advised to employ goodness-of-fit tests as a check on results of t-tests particularly when the latter indicate ‘significance’.     

The Year in Review: Economics at the Antitrust Division 2003–2004

This paper covers the activities of the Economic Analysis Group (EAG), during 2003–2004. It describes the economic analysis undertaken by EAG in several important investigations, litigations, and administrative and appellate matters.The authors are, respectively, Deputy Assistant Attorney General for Economics, U.S. Department of Justice, Antitrust Division, and Economics Director of Enforcement, U.S. Department of Justice, Antitrust Division. The views contained herein are solely those of the authors and do not necessarily represent those of the U.S. Department of Justice.