Unlike cigarette or alcohol taxes, the proposed levy on sweet drinks would not have to be paid by consumers at the time of purchase. That opens a host of pricing options that could thwart the mayor's plan to rein in Philadelphians' half-liter-a-day sugary-drink habit. Nonetheless, for all the pricing experiments retailers are likely to try, the sheer size of the tax – twice as high as proposals under consideration elsewhere – ultimately would lead to significant price increases for sugary drinks at most businesses. "Prices have got to go up. Clearly you can't just absorb this tax; it's too big to eat," said Eric Eisenstein, an assistant professor at Temple University's Fox School of Business.