Questions and Answers of Fundamentals of Biostatistics

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
Implement the test in Problem 8.79, and report a two-sided p-value?Mental HealthA study was performed looking at the effect of physical activity on cognitive function among adults at high risk for
What test can be performed to compare the mean change in the two groups at 18 months?Mental HealthA study was performed looking at the effect of physical activity on cognitive function among adults
What is the standard deviation of change in the control group?Mental HealthA study was performed looking at the effect of physical activity on cognitive function among adults at high risk for
Obtain a frequency distribution, and subdivide infants as high or low according to whether they are above or below the median value for the indices. Use hypothesis-testing and CI methodology to
Answer Problem 8.75 in a different way by subdividing the salt- and sugar-taste indices more finely (such as quintiles or deciles). Compare mean blood-pressure level for children at the extremes
What is the standard deviation of change in the exercise group? Mental HealthA study was performed looking at the effect of physical activity on cognitive function among adults at high risk for
Compare the level of mean FEV between smokers and nonsmokers separately for 10- to 14-year-old boys, 10- to 14-year-old girls, 15- to 19-year-old boys, and 15- to 19-year-old girls?
Compare the level of mean FEV between males and females separately in three distinct age groups (5−9, 10−14, and 15−19 years)?
For each active-hormone group, categorize dosage by high dose (above the median) vs. low dose (at or below the median) and assess whether there is any dose-response relationship (any differences in
Compare the changes in secretion rate or pH levels for each active hormone vs. the placebo (saline) group. Use methods of hypothesis testing and/or CIs to express these comparisons
Assess whether there are significant changes in secretion rates or pH levels with any of the hormones or with saline?Table 8.22: Format of HORMONE.DAT Variable Column Description/Code ID A ID
Perform the test mentioned in Problem 8.68, and report a p-value?CardiologyA clinical trial compared percutaneous transluminal coronary angioplasty (PTCA) with medical therapy in treating
What test can be performed to compare the mean change in duration of exercise between the two treatment groups?CardiologyA clinical trial compared percutaneous transluminal coronary angioplasty
Perform the test in Problem 8.66 for the medical therapy group, and report a p-value?CardiologyA clinical trial compared percutaneous transluminal coronary angioplasty (PTCA) with medical therapy in
Suppose we want to use the procedure in Problem 8.49 using a one-sided test in which the alternative hypothesis is that men have higher cholesterol levels than women. State the hypotheses being
Suppose we want to use the procedure in Problem 8.49 using a two-sided test. State the hypotheses being tested, and implement the method. Report a p-value?GeneticsA study was conducted of genetic and
Of the 15 new MI cases in the preceding study, 5 died within 24 hours. Test whether the 24-hour case fatality rate changed from 2000 to 2010.Suppose that 25% of patients with MI in 2000 died within
Are the assumptions in Problem 8.49 likely to hold for these samples? Why or why not?GeneticsA study was conducted of genetic and environmental influences on cholesterol levels. The data set used for
What test can be used to determine whether the mean change in FEV differs between the high-ozone and low-ozone days?Pulmonary DiseaseA study was performed looking at the effect of mean ozone exposure
Implement the test in Problem 8.53, and report a p-value (two-tailed)?Pulmonary DiseaseA study was performed looking at the effect of mean ozone exposure on change in pulmonary function. Fifty hikers
What test can be performed to test for change in mean total duration of exercise for a specific treatment group? CardiologyA clinical trial compared percutaneous transluminal coronary
Suppose we determine a 95% CI for the true mean change in pulmonary function on high-ozone days. Is this CI narrower, wider, or the same width as a 90% CI? (Do not actually compute the CI.)Pulmonary
What test can be performed to compare the variances of the two genotype groups? Cardiovascular DiseaseLipolysis is a regulator of energy metabolism. Genes encoding proteins that regulate energy
Perform the test in Problem 8.56 and report a two tailed p-value?Cardiovascular DiseaseLipolysis is a regulator of energy metabolism. Genes encoding proteins that regulate energy metabolism through
Suppose we wish to perform a test to compare the means of the two genotype groups. State the hypotheses to be tested, the algebraic form of the test statistic used to test the hypotheses, and the
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 8.56€“8.59? Cardiovascular DiseaseLipolysis is a
Suppose another investigator wants to reproduce the results of the Amish study. She can recruit 100 subjects with the II genotype and 100 subjects with the ID genotype. How much power will the study
What test can be used to determine whether the mean balance score is the same for RA and OA patients? What are some assumptions of this test? RheumatologyA study was conducted [12] comparing
Perform the test mentioned in Problem 8.62, and report a p-value?RheumatologyA study was conducted [12] comparing muscle function between patients with rheumatoid arthritis (RA) and osteoarthritis
What is your best estimate of the proportion of RA and OA patients with impaired balance, where impaired balance is defined as a balance score ‰¤2 and normality is assumed?RheumatologyA
Suppose a larger study is planned. How many participants are needed to detect a difference of 1 unit in mean balance score with 80% power if the number of participants in each group is intended to be
If we assume (a) serum cholesterol is normally distributed, (b) the cholesterol levels within each sample consist of independent observations, and (c) the standard deviations for men and women are
Assess whether there is any difference between the nifedipine and propranolol groups regarding their effects on blood pressure and heart rate. Refer to the indices of change defined in Problems
Provide a 95% CI associated with your estimate in Problem 8.46?Renal DiseaseTen patients with advanced diabetic nephropathy (kidney complications of diabetes) were treated with captopril over an
What is your best estimate of the percent change in urinary protein based on the data in Table 8.16?Renal DiseaseTen patients with advanced diabetic nephropathy (kidney complications of diabetes)
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 DiseaseTen patients with advanced diabetic
What is the appropriate statistical procedure to test whether mean urinary protein has changed over the 8-week period? Renal DiseaseTen patients with advanced diabetic nephropathy (kidney
Suppose the results of Problem 8.41 show no significant difference. Does this mean this type of assessment is highly reproducible? Why or why not?Infectious DiseaseThe degree of clinical agreement
Compute a 95% CI for the true mean difference between observers. How does it relate to your answer to Problem 8.41?Infectious DiseaseThe degree of clinical agreement among physicians on the presence
Perform the test in Problem 8.40, and report a p-value?Infectious DiseaseThe degree of clinical agreement among physicians on the presence or absence of generalized lymphadenopathy was assessed in 32
Should a one-sided or a two-sided test be performed? Why?Infectious DiseaseThe degree of clinical agreement among physicians on the presence or absence of generalized lymphadenopathy was assessed in
What is the appropriate test procedure to determine whether there is a systematic difference between the assessments of Doctor A vs. Doctor B?Infectious DiseaseThe degree of clinical agreement among
Answer Problem 8.37 assuming a one-sided rather than a two-sided test is used?Suppose 40 children, both of whose parents smoke, and 50 children, neither of whose parents smoke, are recruited for the
How much power would such a study have using a two-sided test with significance level = .05, assuming that the estimates of the population parameters in the pilot study are correct? Suppose 40
Answer the question in Problem 8.35 if the investigators use a one-sided rather than a two-sided test?Pulmonary DiseaseA possible important environmental determinant of lung function in children is
Assuming this is regarded as a pilot study, how many children are needed in each group (assuming equal numbers in each group) to have a 95% chance of detecting a significant difference using a
Provide a 95% CI for the true mean difference in FEV between 5- to 9-year-old children whose parents smoke and comparable children whose parents do not smoke?Pulmonary DiseaseA possible important
Carry out the test in Problem 8.32 using the critical value method?Pulmonary DiseaseA possible important environmental determinant of lung function in children is the amount of cigarette smoking in
What is the appropriate test procedure for the hypotheses in Problem 8.31?Pulmonary DiseaseA possible important environmental determinant of lung function in children is the amount of cigarette
What are the appropriate null and alternative hypotheses to compare the means of the two groups? Pulmonary DiseaseA possible important environmental determinant of lung function in children is
Provide a 99% CI for the mean difference in median gray levels between cataractous and normal eyes?OphthalmologyA camera has been developed to detect the presence of cataract more accurately. Using
Carry out the test procedure mentioned in Problem 8.28, and report a p-value?OphthalmologyA camera has been developed to detect the presence of cataract more accurately. Using this camera, the gray
What statistical procedure can be used to test whether there is a significant difference in the median gray levels between cataractous and normal eyes? OphthalmologyA camera has been developed
Provide a 95% CI for the difference in mean CO between the smoking and nonsmoking working environments?Pulmonary DiseaseA 1980 study was conducted whose purpose was to compare the indoor air quality
Test for whether or not the mean CO is significantly different in the two types of working environments?Pulmonary DiseaseA 1980 study was conducted whose purpose was to compare the indoor air quality
Test for whether the standard deviation of CO is significantly different in the two types of working environments?Pulmonary DiseaseA 1980 study was conducted whose purpose was to compare the indoor
Report a p-value for the test performed in Problem 8.23?Cardiovascular Disease, PediatricsA study in Pittsburgh measured various cardiovascular risk factors in children at birth and during their
Test for a significant difference in mean heart rate between Caucasian and African American newborns?Cardiovascular Disease, PediatricsA study in Pittsburgh measured various cardiovascular risk
Compare the mean change in intraocular pressure in the two groups identified in Problems 8.19 and 8.20 using hypothesis-testing methods?OphthalmologyThe drug diflunisal is used to treat mild to
Compute 95% CIs for the mean change in pressure in each of the two groups identified in Problems 8.19 and 8.20?OphthalmologyThe drug diflunisal is used to treat mild to moderate pain due to
The change in intraocular pressure after administration of diflunisal among 30 patients whose standard therapy was topical drugs only was −0.7 ± 2.1 mm Hg. Assess the statistical significance of
Suppose the change (mean ± sd ) in intraocular pressure after administration of diflunisal (follow-up – baseline) among 10 patients whose standard therapy was methazolamide and topical glaucoma
Compute a 95% CI for the true difference in mean white blood cell count between the two groups?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the
What is the p-value corresponding to your answer to Problem 8.16?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56 ± 0.64.
Test for a significant difference between the variances of the two groups?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56
What is the appropriate procedure to test for a significant difference in means between the two groups? NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of
Implement the procedure in Problem 8.3 using the critical-value method?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56 ±
What is the p-value corresponding to your answer to Problem 8.4?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56 ± 0.64.
Compute a 95% CI for the difference in means between the two groups?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56 ±
Suppose an equal number of 12- to 14-year-old girls below and above the poverty level are recruited to study differences in calcium intake. How many girls should be recruited to have an 80% chance of
Answer Problem 8.7 if a one-sided rather than a two sided test is used?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56 ±
Using a two-sided test with α = .05, answer Problem8.7, anticipating that two girls above the poverty level will be recruited for every one girl below the poverty level who is recruited?NutritionThe
Perform the procedure in Problem 8.15 using the critical-value method?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is 6.56 ±
Suppose 50 girls above the poverty level and 50 girls below the poverty level are recruited for the study. How much power will the study have of finding a significant difference using a two-sided
Answer Problem 8.10 assuming a one-sided rather than a two-sided test is used?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age, below the poverty level is
Suppose 50 girls above the poverty level and 25 girls below the poverty level are recruited for the study. How much power will the study have if a two-sided test is used with α = .05?NutritionThe
Answer Problem 8.12 assuming a one-sided test is used with Î± = .05.Table 2.13 Hospital-stay dataNutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14
Test for a significant difference in the variances of the initial white blood cell count between patients who did and patients who did not receive a bacterial culture?NutritionThe mean ±1 sd of ln
What is the appropriate test procedure to test for significant differences in mean white blood cell count between people who do and people who do not receive a bacterial culture?NutritionThe mean ±1
Find the lower 2.5th percentile of an F distribution with 14 and 7 df. What symbol is used to denote this?NutritionThe mean ±1 sd of ln [calcium intake (mg)] among 25 females, 12 to 14 years of age,
Do the SEER rates provide a good fit with the Nurses€™ Health Study incidence data? Perform a separate test for each age group and simply report p > .05 or p < .05. The data in
What is the probability that a 40-year-old woman will develop colon cancer over the next 20 years (i.e., from age 40.0 to age 59.9)?CancerData from the Surveillance Epidemiology and End Results
What is the probability that a 40-year-old woman will develop colon cancer over the next 5 years? CancerData from the Surveillance Epidemiology and End Results (SEER) registry provides incidence
What is the lifetime risk (from age 15 to age 70) of testicular cancer for men with age at surgery = 15, assuming that the incidence rate remains constant over time? Assume that all men do not die of
Is there a significant difference (p < .05) between the incidence of testicular cancer in men treated surgically for undescended testis at age 13–15 vs. the general population?It was reported
Provide a 95% CI for the number of events among men who were 13–15 years at age of surgery?It was reported that the standardized incidence rate in this group compared with men in the general
What is the expected number of events in the general population over 22,884 person-years of follow-up? It was reported that the standardized incidence rate in this group compared with men in the
What is the estimated incidence rate of testicular cancer among this group of men? Express the rate per 100,000 person-years?CancerA study was conducted in Sweden to relate the age at surgery for
Controversy persists about whether statins reduce risk of cardiovascular events entirely through their effects on cholesterol levels or whether other pathways, such as reductions in inflammation, are
Suppose the expected 2-year risk of a major cardiovascular event in similar but untreated people is 0.028. Test whether the 2-year risk in those treated with a statin is significantly different from
Assuming that risk remains constant over time, give an estimate of the 10-year risk of a major cardiovascular event on statin therapy?Cardiovascular DiseaseTreatment with statins can reduce the risk
Estimate the 2-year risk, and give a 95% confidence interval for this estimate?Cardiovascular DiseaseTreatment with statins can reduce the risk of a major cardiovascular event in people with
Suppose we wish to test the hypothesis H0: μ = 2 vs. H1: μ ≠ 2. We find a two-sided p-value of .03 and a 95% CI for μ of (1.5, 4.0). Are these two results possibly compatible? Why or why not?
What is the 25th percentile of a χ2 distribution with 20 degrees of freedom? What symbol is used to denote this value?
Suppose the new drug is hypothesized to yield a fracture rate of 2.5% over a 4-year period. How many subjects need to be studied to have an 80% chance of detecting a significant difference between
Provide a 95% CI for the rate of abdominal pain among the active treated women. Interpret the results compared with previous natural history studies?Suppose that 8 of the previous 100 women have
Is there a significant difference between the fracture rate in individual treated women and the fracture rate in the untreated women? (Report a two-tailed p-value.)EndocrinologyOsteoporosis is an
Implement the procedure in Problem 7.103 to address the question of whether the regimens are equivalent?A goal of the study was to establish whether switching to medication C is “equivalent” to
What procedure can be used to establish equivalence? Is equivalence the same as accepting the null hypothesis in Problem 7.101? Why or why not? A goal of the study was to establish whether

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