Researchers often use z-tests to compare their samples to knownpopulation norms. The Graded Naming Test (GNT) asks respondents toname objects in a set of 30 black-and-white drawings. The testoften used to detect brain damage, starts with easy words likekangaroo and gets progressively more difficult, ending with wordslike sextant. The GNT population norm for adults in England is20.4. Roberts (2003) wondered whether a sample of Canadian adultshad different scores than adults in England. If they weredifferent, the English norms would not be valid for use in Canada.The mean for 30 Canadian adults was 17.5. For the purposes of thisexercise, assume that the standard deviation of the adults inEngland is 3.2.
Some words on the GNT are more commonly used in England. Forexample, a mitre, the headpiece worn by bishops, is worn by thearchbishop of Canterbury in public ceremonies in England. NoCanadian participant correctly responded to this item, whereas 55%of English adults correctly responded. Explain why we should becautious about applying norms to people different from those onwhom the test was normed.
