Use to evaluate the data from a 2x2 crossover design and determine whether the effects of a test drug are equivalent to the effects of a reference drug. For example, you can determine whether the rate of absorption for a new generic pill is equivalent to that of well-established medication.

You can also evaluate whether the test mean is greater than or less than the reference mean.

You want to determine whether your generic antacid is equivalent to a name-brand antacid. Two groups of participants receive a 5-day course of one antacid, followed by a 2-week washout period, and then a 5-day course of the other antacid. You measure gastric pH on the last day of each treatment. Because lower pH values are more acidic, higher values mean the drug is more effective. You will consider the antacids equivalent if the test pH is within 10% of the reference pH.

Group 1 receives the generic antacid (the test treatment) followed by the name-brand antacid (the reference treatment). Group 2 receives the name-brand antacid followed by the generic antacid.

Data: StomachAcid.MTW (available in the Sample Data folder).