Homework 3 | Complete Solution

Patient number   I0PA + B (mm Hg)                  IOPC (mm Hg)
           1               18.0                                         14.5
           2               16.0                                         18.0
           3               17.0                                         11.5
           4               18.0                                         18.0
           5               20.0                                         21.0
           6               19.0                                         22.0
           7               19.0                                         24.0
           8               12.0                                         14.0
           9               17.0                                         16.0
           10              21.5                                        19.0
(you can use SPSS)

Ophthalmology
A study was performed among patients with glaucoma, an important eye disease usually manifested by high intraocular pressure (IOP); left untreated, glaucoma can lead to blindness. The patients were currently on two medications (A and B) to be taken together for this condition. The purpose of this study was to determine whether the patients could drop medications A and B and be switched to a third medication (medication C) without much change in their IOP. Ten patients were enrolled in the study. They received medications A + B for 60 days and had their IOP measured at the end of the 60- day period (referred to as IOPA+B). They were then taken off
medications A and B and switched to medication C, which they took for an additional 60 days. IOP was measured a second time at the end of the 60-day period while the patient was on medication C (referred to as IOPC). The results were as shown in Table 1.

Table 1. Effect of medication regimen on IOP among glaucoma patients

Part1
Q1.1/ What procedure can be used to test the hypothesis that there has been no mean difference in IOP after 60 days between the two drug regimens?

Q1.2/Perform the procedure mentioned in question No.1, and report a two-tailed p-value.

Part2
A goal of the study is to establish whether switching to medication C is “equivalent” to the original regimen of medication A and B. “Equivalence” here means that the underlying mean IOP after switching to medication C has not changed by more than 2 mm Hg in either direction.
Q1.3/What procedure can be used to establish equivalence? Is equivalence the same as
accepting the null hypothesis in question 1.1? Why or why not?

Q1.4/Implement the procedure in question1.3 to address the question of whether the regimens are equivalent.