The article “Irritated by Spam Get Ready for Spit° (USA Today, November 10, 2004) predicts that “spit,” spam that is delivered via Internet phone lines and cell phones, will be a growing problem as more people turn to web-based phone services. In a 2004 poll of 5500 cell phone users conducted by the Yankee Group, 20% indicated that they had received commercial messages or ads on their cell phones. Is there sufficient evidence to conclude that the proportion of cell phone users who have received commercial messages or ads in 2004 was greater than the proportion of .13 reported for the previous year?
