Key points are not available for this paper at this time.
Editor's Note: A new Short Communications section has been added to JBES. This section will include short papers and notes on topics of interest to readers, including measurement problems, revisions of major business and economic time series, forecasting experiments, computer programs, experience with applications of new methods, and comments on previously published papers. To submit papers to be considered for Short Communications, send four copies prepared in accord with ASA guidelines (see JBES, 1, January 1983, 86-89) to the editor. All papers received will be referred to associate editors for refereeing.
Peters et al. (Mon,) studied this question.