questions 6-8

Child Health and Development Studies (CHDS) has been collecting Select one answer. data about expectant mothers in Oakland, CA since 1959. One of the |10 points measurements taken by CHDS is the age of first time expectant mothers. Suppose that CHDS finds the average age for a first time mother is 26 years old. Suppose also that, in 2015, a random sample of 50 expectant mothers have mean age of 26.5 years old, with a standard deviation of 1.9 years. At the 5% significance level, we conduct a one-sided T-test to see if the mean age in 2015 is significantly greater than 26 years old. Statistical software tells us that the p-value = 0.034. Which of the following is the most appropriate conclusion? A. o There is a 3.4% chance that a random sample of 50 expectant mothers will have a mean age of 26.5 years old or greater if the mean age for a first time mother is 26 years old. B. . There is a 3.4% chance that mean age for all expectant mothers is 26 years old in 2015. C. o There is a 3.4% chance that mean age for all expectant mothers is 26.5 years old in 2015. D. . There is 3.4% chance that the population of expectant mothers will have a mean age of 26.5 years old or greater in 2015 if the mean age for all expectant mothers was 26 years old in 1959. Question 7 A researcher conducts an experiment on human memory and Select one answer. recruits 15 people to participate in her study. She performs the 10 points experiment and analyzes the results. She uses a t-test for a mean and obtains a p-value of 0.17. Which of the following is a reasonable interpretation of her results? A. o This suggests that her experimental treatment has no effect on memory. B. . If there is a treatment effect, the sample size was too small to detect it. C. . She should reject the null hypothesis. D. . There is evidence of a small effect on memory by her experimental treatment. Question 8 A criminal investigator conducts a study on the accuracy of Select one answer. fingerprint matching and recruits a random sample of 35 people to 10 points participate. Since this is a random sample of people, we don't expect the fingerprints to match the comparison print. In the general population, a score of 80 indicates no match. Scores greater than 80 indicate a match. If the mean score suggests a match, then the fingerprint matching criteria are not accurate. The null hypothesis is that the mean match score is 80. The alternative hypothesis is that the mean match score is greater than 80. The criminal investigator chooses a 5% level of significance. She performs the experiment and analyzes the results. She uses a t-test for a mean and obtains a p-value of 0.04. Which of the following is a reasonable interpretation of her results? A. . This suggests that there is evidence that the mean match score is greater than 80. This suggests that the fingerprint matching criteria are not accurate. B. . If there is a treatment effect, the sample size was too small to detect it. This suggests that we need a larger sample to determine if the fingerprint matching criteria are not accurate. C. . She cannot reject the null hypothesis. This suggests that the fingerprint matching criteria could be accurate. D. . This suggests that there is evidence that the mean match score is equal to 80. This suggests that the fingerprint matching criteria is accurate