eye gre 4step Does eye grease work? In one study, 16 student subjects took a test of sensitivity to contrast after three hours fac- ing into bright sun, both with and without eye grease. This is a matched pairs design. If eye grease is effective, subjects will be more sensitive to contrast when they use eye grease. Here are the differences in sensitivity, with eye grease minus without eye grease: 12 EYEGRS 0.14 -0.16 0.03 0.05 0.29 0.07 0.64 -0.12 -0.05 -0.18 0.05 0.02 0.43 0.24 -0.11 0.28 Kathy Willens/AP Images W We want to know whether eye grease increases sensitiv- ity on the average. (a) What are the null and alternative hypotheses? Say in words what mean your hypotheses concern. (b) Suppose that the subjects are an SRS of all young people with normal vision, that contrast differences follow a Normal distribution in this population, and that the standard deviation of differences is