In: Statistics and Probability
5. Suppose that researchers study a sample of 50 people and nd that 10 are left-handed.
(a) Find a 95% confidence interval for the population proportion that is left-handed.
(b) What would the confidence interval be if the researchers used the Wilson value ~p instead?
(c) Suppose that an investigator tests the null hypothesis that the population proportion is 18% against the alternative that it is less than that. If = 0:05 then nd the critical value ^pc. Using ^p as the sample estimate, would the investigator reject the null?
(d) Suppose that researchers are using this critical value but, unbeknownst to them, the true, population proportion is 0.16. Find the power of the test.
It is a problem of one sample proportion test with a left tail alternative. Here we also find the confidence interval. All the required theoretical explanations are given in the solution.