An optometrist is interested in the effects of different bra

An optometrist is interested in the effects of different brands of eye drops. She wants to know if different drops affect the accuracy of a standard vision test.

Some researchers think that Brand A may have more adverse effects on an individual’s ability to correctly report the letters in the vision test than Brand B or Brand C. There is also some speculation that the effect of the drops on vision differs dramatically for individuals who are far-sighted compared to those who are near-sighted.

The optometrist hires you to design an experiment that tests the effect of the eye drops on test performance. You tell her there are two possible approaches to take: a randomized comparative approach or a matched pairs design. Describe how you would use each design to test the effect of the eye drops on test performance on a random sample of patients. Remember, there is a concern about the effects for near vs. far-sighted patients. As much as possible, use diagrams instead of words to summarize your experimental design.

Solution

Answer:

In randomised comparative approach the sujects are randomly selected and given different treatments with different medicines or processes. Then the effects of the medical treatment are noted, compared and used for getting inference from the experiment.

This is the process we follow:

step-1 samples are taken and divident into two or three groups.

step-2 different groupds are given diff treatments.

Step-3 results are noted

Step-4 results are compared.

Matched pair design:

A matched pairs design is a special case of a randomized block design. It can be used when the experiment has only two treatment conditions; and subjects can be grouped into pairs, based on some blocking variable. Then, within each pair, subjects are randomly assigned to different treatments.