Jet Lag Drug A recent study was conducted to determine whether the drug Nuvigil was effective at helping east-bound jet passengers adjust to jet lag.

Subjects were randomly assigned either to one of three different doses of Nuvigil (low, medium, high) or to a placebo.

Subjects were flown to France in a plane in which they could not drink alcohol or coffee or take sleeping pills, and then were examined in a lab where their state of wakefulness was measured and classified into categories (low, normal, alert).

If we test whether treatments for jet lag are associated with wakefulness, are we doing a test of independence or of homogeneity? Explain.

(Source: A drug's second act: Battling jet lag. New York Times, January 6, 2010.)