Explain any possible flaws in this conclusion [17]:

A drinker consumes more than twice as much beer if it comes in a pitcher than in a glass or bottle, and banning pitchers in bars could make a dent in the drunken driving problem, a researcher said yesterday. Scott Geller, a psychology professor at Virginia Polytechnic Institute and State University in Blacksburg, Va., studied drinking in three bars near campus.… [O]n average, bar patrons drank 35 ounces of beer per person when it came from a pitcher, but only 15 ounces from a bottle and 12 ounces from a glass.