Test 2: Part B- SOCI 3443 Social Statistics CH6 to CH9 Please well prepared this exam using class material to answer these questions and you also have to take Part A: 30 multiple choices in Blackboard. Please type in your name above to prove that you answer this exam by yourself and understand the SHSU school policies in the syllabus. You HAVE TO submit this Exam 2: Part B through Blackboard. If you turn in your assignment in any other format (except .doc, .docx, or pdf format), you will automatically receive a ZERO for not following instructions. Please be attentive of what you submit. We DON'T accept any late work or wrong submission. Please double check your file before submission. You can submit this Part B several times before the deadline, and this means that you are taking responsibilities of your own submission. This exam will be due by 11:59 CST Sunday, March 27th. Name _______________________________________________ 1 Problem set 1: Use the following information to answer questions 1-3 (10 points): A criminologist developed a test to measure recidivism, where low scores indicated a lower probability of repeating the undesirable behavior. The test is normed so that it has a mean of 140 and a standard deviation of 40. 1. What is the percentile rank of a score of 182 (4 pts)? 2. What percentage of scores falls between 60 and 180 (4 pts)? 3. Suppose an individual is in the 79.10th percentile in this test, what is his or her corresponding recidivism score (2 pts)? 2 Problem set 2: use the following information to answer questions 4-7 (10 points total): An upper-level sociology class at a large urban university has 120 students, including 22 seniors, 68 juniors, 12 sophomores, and 18 freshmen. 4. Imagine that you choose one random student from the classroom (perhaps by using a random number table). What is the probability that the student will be a junior (2 pts)? 5. What is the probability that the student will be a freshman (2 pts)? 6. If you are asked to select a proportionate stratified sample of size 30 from the classroom, stratified by class level (senior, junior, etc.), how many students from each group will there be in the sample (4 pts)? 7. If instead you are to select a disproportionate sample of size 28 from the classroom, with equal numbers of students from each class level in the sample, how many freshmen will there be in the sample (2 pts)? 3 Problem set 3: use the following information to answer questions 8-12 (10 points total): The 2006 General Social Survey contains information on the number of hours worked by a respondent each week. The mean number of hours worked per week is 39.07, with a standard deviation of 12.51. The sample size is 121. 8. Estimate the value of the standard error (2 pts). 9. Calculate a 95 percent confidence interval for these data (2 pts). 10. Provide a one or two sentence interpretation of this result (2 pts). 11. Using this data, provide a hypothetical numerical example which demonstrates that the precision of a confidence interval is in part a function of sample size (2 pts). 12. Using this data, provide a hypothetical numerical example which demonstrates that the precision of a confidence interval is a function of both sample size and the level of confidence (2 pts)? 4 Problem set 4: use the following information to answer questions 13-14 (5 points total): The GSS 2010 measures the amount of hours individuals spend on the Internet per week. Men use the Internet 10.17 hours per week (standard deviation = 11.71, N = 118), while women use the Internet 9.08 hours per week (standard deviation = 12.26, N = 157). 13. Test the research hypothesis that men use the Internet more hours than women, set alpha at .05 (4 pts)? 14. Would your decision have been different if alpha were set at .01 (1 pt)? 5 Problem set 5: use the following information to answer questions 15-17 (5 points total): Suppose you are interested in comparing the mean number of hours worked by sex. Weekly Hours Worked Women Range 59 Minimum value 11 Maximum value 70 Mean Variance 37.28 142.88 Standard deviation 11.95 Sum 2013 Number of observations 54 Weekly Hours Worked Men Range 60 Minimum value 5 Maximum value 65 Mean Variance 42.31 100.00 Standard deviation 10.00 Sum 1,227 Number of observations 29 15. Use all or some of the information above to calculate the value of the independent samples t- statistic (3 pts). 16. Suppose you are interested in comparing the mean number of hours worked by sex. Using the information above, calculate the number of degrees of freedom associated with an independent samples t-statistic (2 pts). 6 17. Define Type I and Type II error (Extra 4 pts). 7