1. (2) A certain drug is tested for its effect on blood pressure. Seven male patients have their systolic blood pressure measured before and after receiving the drug. What is the outcome variable? 2. (1) The following data are the numbers of people who have called the New York State Center for Environmental Health's hotline for the past two weeks: 9, 15, 3, 8, 8, 11, 7, 12, 11, 15 What is the mean number of calls for the two weeks? Write your answer to the nearest tenths. 3.(1) The following data are the numbers of people who have called the New York State Center for Environmental Health's hotline for the past two weeks: 9, 15, 3, 8, 8, 11, 7, 12, 11, 15 What is the median number of calls? 4. Des Jarles et al. examined the failure to maintain AIDS risk reduction in a study of intravenous drug users from NYC. The following table shows the study subjects cross-classified according to risk reduction status (practices risk reduction) and number of sexual partners in an average month: Number of sexual partners/month None 1 >1 None 20 37 20 Risk reduction status Not maintained Maintained (occasionally) (always) 17 43 45 95 54 67 a. (2) What is the measurement scale of risk reduction status? b. (2) What is the measurement scale of number of sexual partners/month? c. (2) What is the probability of a randomly selected person having one sexual partner in an average month? d. (2) What is the probability of a person who has one sexual partner in an average month having a risk reduction status of none? e. (2) What is the probability of a person whose risk reduction status is none having one sexual partner in an average month? 5. The stress scores (on a scale 1 to 10) of students before a statistics test are found to be approximately normally distributed with a mean of 7.08 and a s.d. of .63. Find the probability that the stress score before a statistics test for a randomly selected student will be: a. (3) more than 6.25 b. (3) between 7.4 and 8.9 c. (3) between 3.4 and 6.2 6. (1)Nine men with a genetic condition that causes obesity entered a weight reduction program. After four months the statistics of weight loss were XBAR = 11.2, S = 9.0. Provide a 95% confidence interval for the mean of the population of which this is a sample (assuming normality and randomness). 7. (1) In a survey study on the incidence of depression in a population of psychiatric hospital administrators, scores on a depression measure were obtained from 86 respondents. The observed mean score was 62, with a standard deviation of 16. What kind of table would you use in constructing a 99% confidence interval for the mean depression score? 8. (1) State True or False. As the sample size (n) increases, the mean of a random sample is less likely to be near the mean of the population. 9. (1) Which of the following is a true statement regarding the comparison of t-distributions to the standard normal distribution? a. The normal distribution is symmetrical whereas the t-distributions are slightly skewed. b. The proportion of area beyond a specific value of t is less than the proportion of area beyond the corresponding value of z. c. The greater the df, the more the t-distributions resemble the standard normal distribution. d. All of the above. e. None of the above 10. (2) A sample of size 26 is taken from a normal population. Then a 95% confidence interval is set up with XBAR = 30 and s = 20. The value you would find in the table to complete the information necessary to obtain the interval would be: Select one: a. 1.711 b. 1.708 c. 2.060 d. 2.064 e. 1.960 11. (3 ) A researcher claims that less than 15% of adults in the general US population are allergic to a medication. The results from his study showed that in a random sample of 100 adults only 10 said that they had such an allergy. Test if the researcher's claim is justified (use a one-sided test because you are given the anticipated direction of the difference). - What test will you use? - State H0 and H1 for this test. - Provide the p-value and make a final conclusion about the data using the significance level of 0.05. (Hint: this question is about comparing a proportion to some given value) 12. (4) The Consumer Reports magazine tested two types of winter tires, SnowFlake and SnowMan, to determine how well each brand performs on ice when stopping from 15 mph. 12 sets of the SnowFlake tires and 12 sets of the SnowMan tires were tested. The results showed that for the SnowFlake tires the sample mean stopping distance was 55 feet with the sample standard deviation of 7 feet, while for the SnowMan tires the sample mean stopping distance was 57 feet with the sample standard deviation of 4 feet. Assume that the data are normally distributed. Can you conclude that there is a significant difference in the stopping distance between these two types of tires? - What test(s) will you use? - State H0 and H1 for these tests. - Provide the p-value and make a final conclusion about the data using the significance level of 0.05