(Please refer to the image attached for the data)

Q1. A camera has been developed to detect the presence of cataract more accurately. Using this camera, the gray level of each point (or pixel) in the lens of a human eye can be characterized into 256 gradations, where a gray level of 1 represents black and a gray level of 256 represents white. To test the camera, photographs were taken of 6 randomly selected normal eyes and 6 randomly selected cataractous eyes (the two groups consist of different people). The median gray level of each eye was computed over the 10,000+ pixels in the lens. The data are given in HW4 Q1.sav on Blackboard.

1. What statistical procedure can be used to test whether there is a significant difference in the median gray levels between cataractous and normal eyes? Explain whyusing the appropriate graphs.
2. Carry out the test procedure mentioned in part 1). Use = 0.10, and both rejection region and p-value to make a decision.
3. Provide a 90% CI for the mean difference in median gray levels between cataractous and normal eyes. Interpretthe confidence interval.

PatientID Grey_level Group var 161 Catal N 2 140 Catal W W 136 Catal 4 4 171 Catal UT 106 Catal 6 149 Catal 158 Normal 182 Normal LO 185 Normal 10 10 145 Normal 11 11 167 Normal 12 12 177 Normal 13 14 15