In the years following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent  In contrast, in the year prior to the tax increase, sales had fallen one percent
The volume of cigarette sales is ttherefore strongly related to the after-tax price of a pack of cigarettes
For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year.