1. Compare degree of pain while on Motrin with degree of pain on placebo during maximal activity? 2. Answer Problem 8.81 for degree of pain 12 hours following maximum activity? 3. Answer Problem 8.81...
How large would x have to be for the probability of a normal adult having x or more neutrophils to be 1%? Infectious Disease The differential is a standard measurement made during a blood test. It...
In some studies only values at least 1.5 times as high as the upper limit of normal are identified as abnormal. What percentage of values would fall in this range? Blood Chemistry In pharmacologic...
Implement the test in Problem 9.47, and report a two-tailed p-value?
Answer Problem 10.1 if a one-sided test with power = .8 is used and compliance is perfect? Cardiovascular Disease Consider the Physicians Health Study data presented in Example 10.37 (p. 411).
Answer Problem 10.1 if compliance is as given in Example 10.37? Cardiovascular Disease Consider the Physicians Health Study data presented in Example 10.37 (p. 411).
Suppose a change of 0.30 mg/dL in serum levels is proposed as a test criterion for compliance; that is, a patient who shows a change of ¥ 0.30 mg/dL is considered a compliant vitamin E taker. If...
What percentage of the placebo group would be expected to show a change of not more than 0.30 mg/dL? Cancer A treatment trial is proposed to test the efficacy of vitamin E as a preventive agent for...
Suppose a new threshold of change, Î mg/dL, is proposed for establishing compliance. We wish to use a level of Î such that the compliance measures in Problems 5.36 and 5.38 for the...
What is the relative risk for AMD among women in group 6 compared with women in group 1? What does the relative risk mean in words? Another use for the risk score is to compute a prevalence estimate...
Use regression analysis to relate the number of pack-years smoked to the bone density of the lumbar spine. Assess the goodness of fit of the regression line?
Answer the question in Problem 11.68 for bone density at the femoral neck? One of the issues in relating bone density to smoking is that smokers and nonsmokers differ in many other characteristics...
If the mean plasma-aldosterone level in Caucasian children is 400 pmol/L with standard deviation of 218 pmol/L, then what percentage of Caucasian children have levels 300 pmol/L if normality is...
What is the smallest number of hepatomas that would have to be observed among the alcoholics with cirrhosis of the liver for the hepatoma experience in this group to differ from the hepatoma...
Suppose 10% of the women assigned to the alendronate 5-mg group are actually not taking their pills (noncompliers). If noncompliers are assumed to have a similar response as women in the placebo...
Do you think parametric or non-parametric methods are better suited to analyze the data in VALID.DAT? Explain.
Use logistic-regression methods to compare participants with 1+ episodes of tennis elbow vs. participants with 0 episodes of tennis elbow, considering multiple risk factors in the same model?
In the same study 13 cancers of the digestive tract were observed, whereas only 2 cancers were expected. Are there an unusually high number of digestive cancers among cystic-fibrosis patients?...
Treat testosterone as a continuous variable (suitably transformed if necessary)?
Are there an unusually low number of cancers among cystic-fibrosis patients? Cancer, Neurology A study concerned the risk of cancer among patients with cystic fibrosis [5]. Given registries of...
Suppose the level of pollution has nothing to do with the incidence of heart attack. How many heart attacks would be expected to occur where the pollution level on the index date is higher than the...
Answer Problem 14.39 under this definition of success? To reduce variability, the investigators also considered a criterion of at least 50% improvement on two successive visits as a definition of...
It seems reasonable to assume that more educated people will wait longer before having children. To determine whether this is reasonable draw a scatter diagram of years of education (EDUC) and the...
An auction house conducts an auction once every week listing items such as jewelry, furniture, art, coins, and many others. The number of bidders from each of the auctions over the last 3 years was...
Calculate the mean and standard deviation of the annual incomes (RINCOME). Assuming that the distribution of incomes is very skewed what information do the mean and standard deviation give you?
Find the upper 2.5th percentile of a t distribution with 7 df? Pulmonary Disease The data in Table 6.10 concern the mean triceps skin-fold thickness in a group of normal men and a group of men with...
Find the lower 10th percentile of a t distribution with 28 df? Pulmonary Disease The data in Table 6.10 concern the mean triceps skin-fold thickness in a group of normal men and a group of men with...
Find the upper 1st percentile of a t distribution with 16 df? Pulmonary Disease The data in Table 6.10 concern the mean triceps skin-fold thickness in a group of normal men and a group of men with...
Calculate the mean and standard deviation of household assets (ASSET). Assuming that this variable is positively skewed interpret the two statistics.
Answer Problem 6.12 for a 90% CI. Refer to the data in Table 2.13. Regard this hospital as typical of Pennsylvania hospitals. Table 2.13: Hospital-stay data
Registered Retirement Savings Plan are retirement plans that defer taxes. Many Canadians rely on these plans for their retirement. To measure how these are doing, a random sample of 60-yearold...
What is the standard error of the estimate obtained in Problem 6.15? Refer to the data in Table 2.13. Regard this hospital as typical of Pennsylvania hospitals. Table 2.13: Hospital-stay data
The rising cost of electricity is a concern for homeowners. An economist wanted to determine how much electricity has increased over the past 5 years. A survey was conducted with the percentage...
The sign on the elevator in an office tower states, Maximum Capacity 1,140 kilograms (2,500 pounds) or 16 Persons. A professor of statistics wonders what the probability is that 16 persons would...
Refer to Exercise 9.13. Suppose that the population is not normally distributed. Does this change your answer? Explain.
What is the best estimate of the 1971 incidence rate from these data? Environmental Health Much discussion has taken place concerning possible health hazards from exposure to anesthetic gases. In one...
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...