The adult smoking rate declined, according to an article in Mobile Register, November 11, 2005. The reported results were based on a national household survey of 31,326 adults. People were defined as current smokers if they had smoked at least 100 cigarettes in their lifetime and said they still smoked on a daily or occasional basis. Among American adults, 22.5% in 2002, 21.6% in 2003, and 20.9% in 2004 described themselves as regular puffers.
a Are these results from a sample survey or an experiment? Why?
b Could 20.9% be used as a good estimate of the percent of American population that smokes?