Makers of generic drugs must show that they do not differ significantly from the "reference" drugs they imitate. One aspect in which drugs might differ is their extent of absorption in the blood. The data in the file DrugAbsorption.xls was taken from 20 healthy nonsmoking male subjects for one pair of drugs. This is a matched pairs design. Numbers 1 to 20 were assigned at random to the subjects. Subjects 1 to 10 received the generic drug first, and Subjects 11 to 20 received the reference drug first. In all cases, a washout period separated the two drugs so that the first had disappeared from the blood before the subject took the second.

1. (a) Make a histogram of the differences (use class size of 500) to see that they appear to follow a reasonably Normal distribution with no outliers.

2. (b) Consider the question: Do the drugs differ significantly in absorption? State the null and alternative hypotheses relative to this question.

3. (c) Find the t test statistic.

4. (d) What is the P-value for your t?

5. (e) Do the drugs differ significantly in absorption at significance level ? = 0.05?

   Data privided from Excel below.

                                                                                                                                 

   Subj	Ref	Generic
   15	4108	1755
   3	2526	1138
   9	2779	1613
   13	3852	2254
   12	1833	1310
   8	2463	2120
   18	2059	1851
   20	1709	1878
   17	1829	1682
   2	2594	2613
   4	2344	2738
   16	1864	2302
   6	1022	1284
   10	2256	3052
   5	938	1287
   7	1339	1930
   14	1262	1964
   11	1438	2549
   1	1735	3340
   19	1020	3050