A study is being planned to assess whether a topical antiallergic eye drop is effective in preventing the signs and symptoms of allergic conjunctivitis. In a pilot study, at an initial visit, participants are given an allergen challenge; that is, they are subjected to a substance that provokes allergy signs (e.g., cat dander) and their redness score is noted 10 minutes after the allergen challenge (visit 1 score). At a follow-up visit, the same procedure is followed, except that participants are given an active eye drop in one eye and the placebo in the fellow eye 3 hours before the challenge; a visit 2 score is obtained 10 minutes after the challenge. The data collected are shown in Table 8.26.
Table 8.26 Effect of an eye drop in reducing ocular redness among participants subjected to an allergen challenge
aThe redness score
Suppose 60 participants are enrolled in the main study. How much power would the study have to detect a 0.5-unit mean difference if a two-sided test is used with a significance level of .05?
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Fundamentals of Biostatistics
- The Diabetes Control and Complications trial research group, randomly assigned volunteers with type 1 (insulin-dependent) diabetes mellitus, but without retinopathy, either to a conventional treatment or to a more intensive treatment aimed at maintaining normal blood glucose levels. The volunteers' health was monitored closely for approximately six years. By the end of the study, 91 patients out of 378 in the conventional treatment group had developed retinopathy, whereas 23 out of 348 in the intensive treatment group had developed retinopathy. Test whether the rates of retinopathy differed significantly between the two treatment groups, if they did, which rate was significantly lower. 1. Provide the null hypothesis 2. Provide the alternative hypotheses 3. calculate the appropriate test statistic. Show all work 4. Identify the p-value for that test statistic 5. Using the p-value method and an alpha level of 0.02 state what your conclusions are regarding the null hypothesis, and…arrow_forwardThe Diabetes Control and Complications trial research group, randomly assigned volunteers with type 1 (insulin-dependent) diabetes mellitus, but without retinopathy, either to a conventional treatment or to a more intensive treatment aimed at maintaining normal blood glucose levels. The volunteers' health was monitored closely for approximately six years. By the end of the study, 91 patients out of 378 in the conventional treatment group had developed retinopathy, whereas 23 out of 348 in the intensive treatment group had developed retinopathy. Test wether the rates of retionpathy differed significantly betweenthe two treatment groups, if they did, which rate was significantly lower. 1. Provide the null hypothesis 2. Provide the alternative hypotheses 3. calculate the appropriate test statistic. Show all work 4. Indentify the p-value for that test statistic 5. Using the p-vlaue method and an alpha level of 0.02 state what your conclusions is regarding the null hypothesis, and…arrow_forwardChocolate contains caffeine and an endogenous cannabinoid, as well as a chemical thatmodulates serotonin production; but is it an aphrodisiac, as the Mayans and Aztecs believed?Suppose you conduct a study which measures sex drive in a group of 20 women, after eating 8ounces of chocolate. Given that you have available data from the Kinsey Institute (IndianaUniversity) about the general sex drive for women of the same demographic as in your study, youdecide to compare your group to this population estimate.If testing hypotheses about the effects of chocolate on sex drive, it would be most appropriate tocalculate a ...1)Paired sampled t2)Z-test3)Independent-samples t-test 4)One- sample t-testarrow_forward
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