Stats Chapter 11 & 12 MC Study Guide Exam Questions Fully Solved.

Which one of the following statements is TRUE? - correct answer As the alpha-level increases, the probability of a Type II error of a hypothesis test decreases. A pharmaceutical company has developed a new medication to lower a person's cholesterol. The advertisement for the new drug cites the results of an experiment comparing the drug with a placebo stating that the cholesterol level had been lowered by an average of 13.2 mg/l with a P-value 0.01. Which one of the following best explains the meaning of the P-value? - correct answer If the mean cholesterol levels for the placebo and medication groups were really equal, we would have obtained a difference such as this or more, less than 1% of the time by random chance. How could someone determine if the distribution of sample means is approximately normal? - correct answer II. The sample is large, say greater than 30. III. The parent population is approximately normal. When performing a two-sided hypothesis test by hand, one must be sure to - correct answer double the p-value In hypothesis testing, the null hypothesis is - correct answer a statement of no difference or no change from what one would normally expect if there were no effect of the experimental treatment A type I error is - correct answer the probability of rejecting a true null hypothesis If a hypothesis test is performed and the results are statistically significant at significance level alpha, then - correct answer the p-value is less than alpha Suppose a one-sided hypothesis test gives a p-value of 0.19. One can reject Ho - correct answer at none of the common alpha levels of 0.01, 0.05, or 0.1 The power of a hypothesis test can be increased by all of the following EXCEPT - correct answer calculating the test statistic to more decimal places of accuracy The Environmental Protection Agency is charged with monitoring industrial emissions that pollute the atmosphere and water. So long as emission levels stay within specified guideiines, the EPA does not take action against the polluter. If the polluter is in violation of the regulations, the offender can be fined,forced to clean up the problem, or possibly closed. Suppose that for a particular industry the acceptable emission level has been set at no more than 5 parts per million (5 ppm). The null and alternate hypotheses would be H_0 H 0 : mu=5 μ = 5 versus H_a H a : mu5 μ 5 . Which one of the following describes a Type II error? - correct answer The EPA concludes that emissions are within acceptable limits when, in fact, they exceed acceptable limits. Suppose a 1-sided test gives a test statistic t = 2.45 for a sample size of 24. What conclusion can be made at the alpha = 0.05 level? - correct answer reject Ho at alpha = 0.05 A realtor is interested in the average price of homes in his state. He randomly selects 16 homes and records the prices. Under what conditions could t procedures be safely used in this situation? - correct answer t procedures can be used in this situation as long as the graph of the data shows no outliers or strong skewness A local coffee shop decided to start advertising on the radio. The 12 weeks following a lengthy advertising campaign showed sales averaging $5785.34 per week with a standard deviation of $385.23. This compares to an average of $5355 per week in sales before the advertising campaign. Assuming the conditions are met, does this data give convincing evidence that the advertising campaign increased sales? - correct answer Yes, at all common alpha levels An exercise physiologist is interested in the effect of exercise on heart rate. She has subjects walk slowly for 5 minutes and record their heart rates. Then she has the subjects run vigorously for 5 minutes and records their heart rates again. The differences are recorded (heart rate after running - heart rate before running) with the results below: One-Sample T: Differences Test of mu = 0 vs. = o Variable N Mean StDev SE Mean 95% CI T P differences 12 59.88 10.36 3.66 (51.22,68.53) 16.35 0.00 What is a valid interpretation of the hypothesis test given from the computer output? - correct answer strong evidence exists of an increase in heart rate Travis recently heard a report claiming that 35% of young adults have at least one tattoo. He thinks that the actual percentage is lower for students at his university. To investigate, he randomly selects 60 students from his university and finds that 17 of them have at least one tattoo. Assuming that all conditions have been met, what is the p-value for the appropriate significance test? Correct Answer - correct answer 0.14