PHILADELPHIA (AP) — A marketing study says Philadelphia's 1.5-cent-per-ounce tax on soda and other sweetened drinks is chasing customers out of the city.

Philly.com reports that the study by the Florida marketing firm Catalina showed sales of such drinks at nearly 1,000 franchised grocery and drug stores have fallen 55 percent, while sales at stores studied just outside the city's border rose 38 percent.

Catalina says the study wasn't paid for by any soft drink companies, but city officials are skeptical of the data. The tax has raised $39.3 million for prekindergarten and other programs, less than the city's initial projection of $42.6 million.

City spokesman Mike Dunn says that Catalina is exaggerating the tax's impact and that it doesn't factor the inconvenience of traveling outside the city to buy the drinks.