An avalanche of articles has described the testing of a time series for the presence of unit roots. However, economic model builders have disagreed on the value of testing and how best to operationalise the tests. Sometimes the characterization of the series is an end in itself. More often, unit...

Managers in the music industry closely monitor both radio airplay of an album as well as the album's sales. Their interest in radio airplay is due to the belief that airplay can increase an album’s sales. Therefore it is natural for managers to attempt to influence radio airplay so as to...