According to a Pew Research Center survey 30% of graduates who had student loans are delinquent (90 or more days behind in their payments. Suppose that a survey of 10 such graduates is taken. a. What...
Can we infer that the Survey of Consumer Finances in 2013 overrepresented at least one education category (EDCL)? Developing an Understanding of Statistical Concepts.
Immigration has become a hot-button issue in American politics. One question that arises is: Are immigrants educational attainments different from those born in the United States? Conduct a test to...
Comment on the comparison between the observed incidence rate and the Connecticut tumor registry data? A comparison was made between the Michigan report and the 1969 cancer-incidence rates from the...
Are some industries better than others in terms of financial remuneration? Conduct a test to determine whether there are differences in income (INCOME) between the three categories of industry.
Has the proportion of Americans who were never married changed since the census? Conduct a test to answer the question (MARITAL: 5 = Never married).
For Exercises 20.4 and 20.5, graph the time series and the two moving averages.
Compute the mean birth-weight for each of the six samples? Table 6.2: Sample of birth-weights (oz) obtained from 1000 consecutive deliveries at Boston City Hospital ID Numbers 0 1 2 3 10 11 12 13 14...
For the following time series, compute the three-period moving averages. Period Time Series Period Time Series 16 24 29 2 22 3 19 21 4 24 10 23 19 26 12 15
Perform the Wilcoxon signed rank sum test for the following matched pairs to determine whether the two population locations differ. (Use α = .10.) 4 3 12 13 9. 5 10 Pair Sample 1 Sample...
What theoretical relationship should there be between the standard deviation in Problem 6.48 and the standard deviation in Problem 6.49? Table 6.2: Sample of birth-weights (oz) obtained from 1000...
Exercise 2.65 described a survey of the business school graduates undertaken by a university placement office. The respondents reported (among other questions) gender (1 = Female, 2 = Male) and area...
Exercise 4.67 addressed the problem of setting an appropriate speed limit on highways. Automotive experts believe that the correct speed is the 85 th percentile. Suppose that the speeds on a highway...
What is the probability that the sample mean will be within 1 unit of the population mean? Suppose we have a population with a normal distribution with mean = 50 and standard deviation = 10. We draw...
Use a computer program to compute the lower 10 th percentile of a t distribution with 54 df? Renal Disease The mean serum-creatinine level measured in 12 patients 24 hours after they received a newly...
Use a computer program to compute the probability that a t distribution with 36 df exceeds 2.5? Renal Disease The mean serum-creatinine level measured in 12 patients 24 hours after they received a...
Construct a stem-and-leaf display for the following data: 34 25 46 75 15 81 69 72 15 19 64 67 62 24 57 27 48 35 41 64 51 48 42 77 71 38 20 26 83 21
If the mean and standard deviation of serum creatinine in the general population are 1.0 and 0.4 mg/dL, respectively, then, using a significance level of .05, test whether the mean serum-creatinine...
Which of the following sample results yields a 95% CI for with the smallest width and why? (i) x = 28, s = 5, n = 61 (ii) x = 32, s = 4, n = 30 (iii) x = 25, s = 3, n = 20 (iv) x = 40, s = 6, n =...
Test the hypothesis that the incidence rate of nausea for the erythromycin group is the same for a typical pregnant woman? Obstetrics The drug erythromycin has been proposed to possibly lower the...
Based on your results and responses to the previous questions, does the screening test appear to be potentially useful as one of the factors in helping Baldwin predict whether a given applicant will...
The U.S. Department of Transportation reports that America West Airlines got 7.65 complaints of mishandled baggage per 1000 passengers in March 2000. Assuming this rate applies to the next 500...
In the past, patrons of a cinema complex have spent an average of $2.50 for popcorn and other snacks, with a standard deviation of $0.90. The amounts of these expenditures have been normally...
Answer Problem 7.9 if the expected difference is 0.20 ln units? Diabetes Plasma-glucose levels are used to determine the presence of diabetes. Suppose the mean ln (plasma-glucose) concentration...
How many people would need to be studied to have 80% power under the assumptions in Problem 7.9? Diabetes Plasma-glucose levels are used to determine the presence of diabetes. Suppose the mean ln...
During 2000, 3.2% of all U.S. households were burglary victims. For a simple random sample of 300 households from a certain region, suppose that 18 households were victimized by burglary during that...
What is the approximate standard error of the mean for the high-fiber compared with the low-fiber diet (that is, the mean difference in cholesterol level between high- and low-fiber diets)?...
Differentiate between the Wilcoxon signed rank test and the Wilcoxon rank sum test, and explain the circumstances under which each should be applied.
How many participants would be needed to have a 90% chance of finding a significant difference in mean cholesterol lowering between the high- and low-fiber diets if the high-fiber diet lowers mean...
What is the parametric counterpart to the Wilcoxon rank sum test? Compare the assumptions involved in using the respective tests.
A word-processing firm has narrowed down its choice of a printer to two major brands. Using a 20-page document that is typical of the firms work, a number of printers of each brand are timed while...
The coefficient of correlation between variables y and x is 0.90. Calculate and interpret the value of the coefficient of determination.
Provide a 95% CI for the incidence rate of neuroblastoma in the screened population. Express the 95% CI as (p 1 , p 2 ), where p 1 and p 2 are in the units of number of cases per 100,000 children. Is...
What procedure can be used to test the hypothesis that there has been no mean difference in IOP after 60 days Data set available between the two drug regimens? Ophthalmology A study was performed...
Testing the null hypothesis that the slope of the true regression line equals zero is equivalent to testing whether the true coefficient of correlation could be zero. Why?
Answer Problem 8.12 assuming a one-sided test is used with α = .05. Table 2.13 Hospital-stay data Nutrition The mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14...
Test for a significant difference between the variances of the two groups? Nutrition The mean 1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56...
Compare the mean change in intraocular pressure in the two groups identified in Problems 8.19 and 8.20 using hypothesis-testing methods? Ophthalmology The drug diflunisal is used to treat mild to...
After you conduct a coin-flipping simulation, a graph of the _______ will be centered very close to 0.50. Choose from (A)(D). A. Process probability B. Sample size C. Number of heads D. Proportion of...
Th e graph of a null distribution will be centered approximately on: A. The observed proportion B. The observed count C. The value of the probability in the null hypothesis D. The number of...
The simulation (flipping coins or using the applet) done to develop the distribution we use to find our p-values assumes which hypothesis is true? A. Null hypothesis B. Alternative hypothesis C. Both...
When we get a p-value that is very large, we may conclude that: A. The null hypothesis has been proven to be true. B. There is strong evidence for the alternative hypothesis. C. The null hypothesis...
When we get a p-value that is very small, we may conclude that: A. The null hypothesis has been proven to be true. B. There is strong evidence for the alternative hypothesis. C. The null hypothesis...
Suppose you are testing the hypotheses H 0 : = 0.25 and H a : < 0.25 and the observed statistic, p is equal to 0.30 with a sample size of 100. a. If you are using a proportion as your statistic,...
Capital punishment for murderers exists in most U.S. states. However, a few states ban this form of punishment. Politicians often need to know which members of the public support and which oppose....
Perform the test in Problem 8.44 using both the raw and ln scale, and report a p-value. Are there any advantages to using the raw or the ln scale? Renal Disease Ten patients with advanced diabetic...
One survey question asked in which industry was the head of the household employed in. One of the categories was mining, construction, or manufacturing, all of which may be in decline. Estimate the...
On average how many units will be produced until the control chart signals that the process is out of control when it is under control? A firm that manufactures notebook computers uses statistical...
Given the following payoff table, draw the decision tree: -1 4 10 S1 S2 S3 20 -10
1. Perform the test in Problem 8.58, and report a two tailed p-value? 2. What are your conclusions based on the analyses in Problems 8.568.59? Cardiovascular Disease Lipolysis is a regulator of...
A baker must decide how many specialty cakes to bake each morning. From past experience, she knows that the daily demand for cakes ranges from 0 to 3. Each cake costs $3.00 to produce and sells for...
How much power did the study have for detecting a significant difference between groups (using a two-sided test with a 5% level of significance) if the true effect of the SMI intervention is to...
The number of hits (views) is recorded at a high-volume Web site in a day. Provide a reasonable description of the sample space. There can be more than one acceptable interpretation of each...
Provide a 95% CI for the difference in mean pod weight between the two groups? Microbiology A study sought to demonstrate that soy beans inoculated with nitrogen-fixing bacteria yield more and grow...
What test can be used to compare the mean pod weight between the two groups? Microbiology A study sought to demonstrate that soy beans inoculated with nitrogen-fixing bacteria yield more and grow...
Suppose two researchers are conducting studies about animal behavior, and they both have the same null hypothesis and the same alternative hypothesis as each other. Also, suppose that Researcher As...
What minimum sample size would be needed to detect a mean change of 5 units with 80% power if a two-sided test is used with = .05? Neurology In a 5-year follow-up of bilateral stimulation of the...
Perform the test in Problem 8.173, and assess whether there is a significant difference between the variances at the 5% level? Orthopedics A study was performed among patients with piriformissyndrome...
Buzz got 15 right out of 16. Suppose the numbers had been exactly double that: 30 right out of 32. a. Which of the three infl uences on strength of evidence (distance, sample size, one- or two-sided)...
Why might a t test not be very useful in this case? Health Services Administration Suppose we want to compare the length of hospital stay for patients with the same diagnosis at two different...
What hypotheses are being tested here? Otolaryngology, Pediatrics A common symptom of otitis media in young children is the prolonged presence of fluid in the middle ear, known as middle-ear...
Just for the sake of this exercise, imagine that the investigators wanted their statistical test to include the possibility that Buzz was a very sadistic dolphin, so malicious that he would willingly...
Why might a nonparametric test be useful in testing the hypotheses? Otolaryngology, Pediatrics A common symptom of otitis media in young children is the prolonged presence of fluid in the middle ear,...
Which nonparametric test should be used here? Otolaryngology, Pediatrics A common symptom of otitis media in young children is the prolonged presence of fluid in the middle ear, known as middle-ear...
Perform the test in Problem 9.17, and report a p-value? Hypertension Polyunsaturated fatty acids in the diet favorably affect several risk factors for cardiovascular disease. The principal dietary...
Suppose we want to compare mean BMI between Caucasian and African American premenopausal women based on the data in the table and are willing to assume the distribution of BMI is approximately...
Compare your results to those obtained using t test methods in Problem 8.107 (p. 329)? Cardiovascular Disease Left ventricular mass (LVM) is an important risk factor for subsequent cardiovascular...
Answer Problem 10.4 if compliance is as given in Example 10.37. Refer to Table 2.13 (p. 36). Table 2.13: Hospital-stay data
Suppose 11,000 men are actually enrolled in each treatment group. What would be the power of such a study if a two-sided test with = .05 were used and compliance is perfect? Cardiovascular Disease...
Do these data show a significant association between ethnic origin and genetic type? Ophthalmology Retinitis pigmentosa is a disease that manifests itself via different genetic modes of inheritance....
Rick is a basketball player who wants to investigate whether he successfully makes more than 90% of his free throws by shooting with an underhand style. a. Define (in words) the relevant parameter of...
What test can be used to compare the prevalence of otorrhea for the ear drop group vs. the observation group? State the hypotheses to be tested? Otolaryngology Many children have tympanostomy tubes...
Summarize the conclusion that you draw from this study and your simulation analysis. Also explain the reasoning process behind your conclusion.
Implement the test in Problem 10.32, and report a p-value? Mental Health A study was performed in Lebanon looking at the effect of widowhood on mortality [14]. Each of 151 widowers and 544 widows...
True or false? A. Larger samples are always better than smaller samples, regardless of how the sample was collected. B. Larger random samples are always better than smaller random samples. C. You...
Can you assess the reproducibility of adverse events and negligence designations? Which seems to be more reproducible? Health Services Administration In the Harvard Medical Practice Study [16], a...
When stating null and alternative hypotheses, the hypotheses are: A. Always about the parameter only B. Always about the statistic only C. Always about both the statistic and the parameter D....
What test can be performed to compare the percentage of participants who developed abnormal triglyceride levels between the vitamin A group and the trace group? Ophthalmology One interesting aspect...
Use the previous information to answer the following questions about the class survey. a. Describe in words the parameter of interest. b. Identify the numeric value of the statistic corresponding to...
In the survey the student also asked students whether or not they watched at least 10 minutes of TV yesterday. Th e student found that 21 of 30 students reported watching at least 10 minutes of TV...
What test can be used to assess whether the feeding preference of goldfinches are the same on different days? One assumption in the entire experiment is that the feeding preferences of the same...
What test can be used to compare cancer incidence rates between the two treatment groups? Cancer The Physicians Health Study was a randomized doubleblind placebo-controlled trial of beta-carotene (50...
Consider how the student obtained her sample for her study. If her study was conducted by taking a random sample, explain (in enough detail that someone could follow your directions to obtain the...
What is the probability of 0, 1, 2, 3, 4, and 5 male offspring out of 5 births based on the estimate in Problem 10.81? Demography A common assumption is that the gender distributions of successive...
Use the previous information to answer the following questions. a. What is the population of interest? b. Do you believe that the proportion of people unhappy with the verdict in the sample is likely...
Implement the test in Problem 10.76, and report a p-value? One assumption in the entire experiment is that the feeding preferences of the same species of bird remain the same over time. To test this...
Answer the question in Problem 10.101 for rapid acetylators. Report a two-tailed p-value? Cancer, Genetics A casecontrol study was performed of renal-cell carcinoma (RCC) (kidney cancer) [25]. The...
Do you think that genetic factors influence the relationship between smoking and RCC based on the preceding data? Why or why not? Cancer, Genetics A casecontrol study was performed of renal-cell...
The monthly salaries of the three people working in a small firm are $3,500, $4,000, and $4,500. Suppose the firm makes a profit and everyone gets a $100 raise. How, if at all, would the average of...
Reconsider the previous exercise where the monthly salaries of the three people working in a small firm are $3500, $4000, and $4500. If instead of a $100 raise, everyone gets a 10% raise, how, if at...
How many women need to be studied in each group (equal sample size per group) to have an 80% probability of detecting a significant difference if a two-sided test is used with a type I error of 5%?...
One problem with the design is that about 20% of the women who are randomized to PMH will not comply (i.e., will go off PMH during the trial). In addition, 10% of the participants in the control...
According to a 2011 report by the U.S. Department of Labor, civilian Americans spend 2.75 hours per day watching television. A faculty researcher, Dr. Sameer, at California Polytechnic State...
Consider the investigation of the manufacturing process that is producing hypodermic needles. Recall that the most recent random sample of 35 needles have an average diameter of 1.64 mm and a...
Perform a simulation study, and generate 100 participants from a binomial distribution with p = .2 and 100 participants from a binomial distribution with p = .1. Test to determine whether the...
Repeat the Problem 10.116 simulation 1000 times, and compute the proportion of simulations in which a significant difference is found (i.e., an estimate of the power of the study)? Simulation Suppose...
What should the theoretical power be for the exercise in Problem 10.117? How do the estimated power and theoretical power compare? Simulation Suppose we are planning a clinical trial and expect a 20%...
What is the expected number of infants in DBP quintile 2 with a preferential salt taste response under the null hypothesis? Hypertension A study was performed relating neonatal blood-pressure level...
Fit a regression line relating the percentage of reticulocytes (x) to the number of lymphocytes (y)? Hematology The data in Table 11.17 are given for 9 patients with aplastic anemia [11]. Table...
Test this correlation for statistical significance, and report a p-value? Cancer The following statistics are taken from an article by Burch relating cigarette smoking to lung cancer [13]. The...