Question

Describe a situation in which you would test a directional hypothesis. Be sure to state the independent variables (e.g., drug or placebo) and the dependent variables (e.g., weight loss) clearly and explain why the hypothesis is directional. Then, revise the same situation to make it nondirectional. Explain which according to you is more appropriate and why. Evaluate the practice of altering the alpha level so that a two-tailed test will have a 5% rejection region on both sides of the curve for a total of 10% instead of having a 2.5% rejection region on both sides in order to maintain a 5% alpha.

Answer 1

Answer:---- Date:---30/7/2020

Assume that effectiveness of a drug for weight loss is to be tested. According to the manufacturer's claim, the mean weight loss per week would be 3kgs. In this case, to check whether the mean weight loss is more than 3 kg., the null and alternative hypothesis would be set as follows: + H,: The mean weight loss per week is not more than 3 kgs (433) H,: The mean weight loss per week is more than 3 kgs (u>3) The above situation is an example for directional test, where in the test is directed towards the right side of 3. In this case, the dosage of drug would be independent variable and weight loss would be dependent variable. The same situation can be re-stated as follows: Check whether the mean weight loss is 3kgs or not. In this case, the null and alternative hypothesis can be set as follows: H : The mean weight loss per week is 3 kgs (4=3) H,: The mean weight loss per week is not 3 kgs (u #3) The above situation is an example for non-directional test, where in the test is directed towards the both sides of 3.