Use the following information for all questions on this page.A physician wants to compare the blood pressures of six patients before and after treatment with a drug. It is believed that the drug will reduce blood pressure. The blood pressures are as follows:

Patient	After Drug	Before Drug	Difference
1	168	171	-3
2	171	170	1
3	182	180	2
4	167	173	-6
5	174	178	-4
6	170	172	-2

The mean difference is -2 with a standard deviation of 3.033

The test statistic is?