Questions and Answers of Fundamentals of Biostatistics

Perform the test in Problem 10.145, and report a p-value (two-tailed)?The results of the study were as follows: 14 of the 50 active intervention children had an improvement in symptoms compared with
What is the principal benefit(s) of assigning patients randomly to the treatment regimens? CardiologyAntithrombotic drugs are used after coronary stenting to prevent stent thrombosis. A study
What are your overall conclusions based on your results?HypertensionA study was performed relating neonatal blood-pressure level to neonatal taste responsiveness (Zinner et al. [29]). To assess salt
Use a computer program to implement this test procedure and report a two-tailed p-value?HypertensionA study was performed relating neonatal blood-pressure level to neonatal taste responsiveness
What test procedure can be used to test the hypotheses in Problem 10.130? HypertensionA study was performed relating neonatal blood-pressure level to neonatal taste responsiveness (Zinner et al.
What is the expected number of infants in DBP quintile 2 with a preferential salt taste response under the null hypothesis? HypertensionA study was performed relating neonatal blood-pressure
State the null and alternative hypotheses to be tested to answer this question in statistical terms?OphthalmologyDry eye is the most prevalent form of ocular discomfort and irritation, with
Treating ocular discomfort as an ordinal scale, assess whether significant differences in ocular discomfort exist between active and placebo patients. Report a p-value (two-tailed). Interpret the
Treating ocular discomfort as a nominal scale, assess whether significant differences in ocular discomfort exist between active drug and placebo patients. Report a p-value
What is the difference between a nominal and ordinal categorical variable? What type of variable is ocular discomfort? OphthalmologyDry eye is the most prevalent form of ocular discomfort and
Suppose the investigators plan a larger study comparing the two tests. How many infants need to be tested to have an 80% probability of finding a significant difference using a two-sided test with
Perform a hypothesis test to compare the accuracy of the two tests, and report a two-sided p-value?A new test is proposed that may be better or worse than the standard test. To assess their relative
What precentage of infants who test positive using the test will actually have Down’s syndrome? Suppose that 1 out of 500 infants are born with Down’s syndrome.
What is the sensitivity and specificity of the test? ObstetricsThe standard screening test for Down’s syndrome is based on a combination of maternal age and the level of serum
How many subjects need to be enrolled in total in the study if (1) the investigators want to have a 90% chance of detecting a significant difference using a two-sided test with α = .05 and (2) it is
Interpret the results of your test in Problem 10.120?After 2 weeks of treatment, 14 of the placebo patients and 3 of the ASA patients developed clinically significant hearing loss.
Implement a test to assess whether the incidence of hearing loss is different between the groups. State clearly which test you are using, and report a two-sided p-value?After 2 weeks of treatment, 14
(i) What is a prospective study? What are its advantages?(ii) What is a randomized study? What are its advantages?(iii) What is a double-blind study? Are there advantages vs. other
What should the theoretical power be for the exercise in Problem 10.117? How do the estimated power and theoretical power compare? SimulationSuppose we are planning a clinical trial and expect a
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)?SimulationSuppose
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
Compare the distribution of BMI between Caucasian and African American women using this finer classification. Report a two-tailed p-value?A more exact classification of BMI is as follows: <25 is
Compare the percentage of Caucasian and African American women who are overweight. Report a two-tailed p-value?
Interpret the results (i.e., do cases have higher, lower, or the same vitamin D3levels as controls?). CancerThere were early reports that people with extensive sun exposure had a reduced risk of
Implement the test in Problem 10.111, and report a two-sided p-value?CancerThere were early reports that people with extensive sun exposure had a reduced risk of colorectal cancer incidence. Garland
What test can be performed to assess whether cases tend to have lower levels of vitamin D3than controls? CancerThere were early reports that people with extensive sun exposure had a reduced risk
In a reproducibility study, researchers contacted the 953 spouses a second time 1 year later and asked them again whether the index subject was schizophrenic. There were 112 positive reports of
Suppose there is no difference in the percentage of subjects identified as schizophrenic by physician and by proxy informants. Does this mean the two sources of information are the same for each
Compare the percentage of subjects identified as schizophrenic by physician report with those so identified by proxy report. Perform a hypothesis test, and report a two-tailed p-value?Suppose nether
If the physician report is considered the gold standard, what is the sensitivity and specificity of proxy reports of schizophrenia?Mental HealthResearchers collected the following data concerning
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
Suppose that 20,000 women are recruited in each group in the actual study. How much power would the study have under the same assumptions just given? CancerThe effect of using postmenopausal
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
Do you think that genetic factors influence the relationship between smoking and RCC based on the preceding data? Why or why not?Cancer, GeneticsA caseˆ’control study was performed of
Answer the question in Problem 10.101 for rapid acetylators. Report a two-tailed p-value?Cancer, GeneticsA caseˆ’control study was performed of renal-cell carcinoma (RCC) (kidney cancer)
Test for the association between the number of cigarettes smoked per day and RCC among slow acetylators. (Report a two-tailed p-value.) Cancer, GeneticsA caseˆ’control study was
Perform the test procedure in Problem 10.99. Provide a p-value. (Assume that BMI is measured exactly with no measurement error; thus, the range 20−22.9 includes all values ≥20 and <23,
The expectation before the study started was that beta-carotene might prevent 10% of incident cancers relative to placebo. How much power did the study have to detect an effect of this magnitude if a
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
What test procedure can be used to assess whether the distribution of BMI among the boys is normal? One issue in comparing BMI between groups is the underlying distribution of BMI. The mean BMI
Perform the test procedure in Problem 10.97, and provide a two-tailed p-value?Health PromotionIt is fairly well known that perception of weight by adolescents does not always agree with actual
What test procedure can be used to assess whether the weight status of boys significantly differs from girls?Health PromotionIt is fairly well known that perception of weight by adolescents does not
Perform the test mentioned in Problem 10.95, and report a two-tailed p-value. What is your conclusion regarding the effectiveness of the undiluted in contrast to the 1:100 diluted vaccine? A
What test can be used to compare the cytotoxic T-cell response of the undiluted group vs. the 1:100 diluted group? A more quantitative measure of efficacy was the cytotoxic T-cell response. The
Perform a test to assess whether the success rate is a function of the log10(dilution ratio). Report a two-tailed p-value. [For the 1:10 group, log10(dilution ratio) = log10(1/10) = −1, . . . ,
Perform a test to compare the success rate of undiluted vaccine vs. 1:100 diluted vaccine. Report a two-tailed p-value?Infectious DiseaseSmallpox vaccine is highly effective in immunizing against
Perform a test to compare the percentage acute OTM-free in the AMX group vs. the PLA group over the second 6 months of the study among children who were acute OTM-free after the first 6 months.
Perform the test in Problem 10.90, and report a two-tailed p-value?OtolaryngologyAcute OTM early in infancy may be an important predictor of subsequent morbidity, including psychological and
What test can be used to compare the percentage of children who were acute OTM-free between the AMX group and the PLA group? OtolaryngologyAcute OTM early in infancy may be an important
If we assume that these 75% of patients had a mortality rate that was the average of the early start and late start groups (i.e., 31%), then how much power did the study actually have under the same
How much power would the study have if it had occurred under the planned mortality rates and sample size? In planning the study it was anticipated that 400 subjects would be enrolled per group
Implement the test in Problem 10.86, and report a two-sided p-value?Renal DiseaseA study was performed among patients with progressive chronic kidney disease to assess the optimal time for the
What test can be used to compare the mortality rates in the two groups? Renal DiseaseA study was performed among patients with progressive chronic kidney disease to assess the optimal time for
Implement the test in Problem 10.84, and report a two-tailed p-value?Pediatrics, UrologyNighttime bladder control is an important developmental milestone, with failure dependent on age. Continence is
What test can be used to assess whether the percentage of cases among boys is significantly different from the percentage of cases among girls? Pediatrics, UrologyNighttime bladder control is an
Test the hypothesis that the gender distributions of successive offspring are independent based on the model in Problem 10.82. What are your conclusions concerning the hypothesis? DemographyA
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? DemographyA common assumption is that the gender distributions of
What is the best estimate of the probability of a male offspring based on the observed data? DemographyA common assumption is that the gender distributions of successive offspring are
Implement the test in Problem 10.78, and report a two-tailed p-value.CancerThe Physicians€™ Health Study was a randomized doubleblind placebo-controlled trial of beta-carotene (50 mg every
What test can be used to compare cancer incidence rates between the two treatment groups? CancerThe Physicians€™ Health Study was a randomized doubleblind placebo-controlled trial of
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
Implement the test in Problem 10.74, and report a p-value?ZoologyA study was performed to look at the preference of different species of birds for different types of sunflower seeds. Two bird feeders
What test can be performed to assess whether the feeding preferences of titmice and goldfinches are comparable on the first day of testing?ZoologyA study was performed to look at the preference of
Implement the test in Problem 10.72, and report a two-tailed p-value?OphthalmologyOne interesting aspect of the study described in Problem 10.68 is to assess changes in other parameters as a result
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? OphthalmologyOne interesting
What proportion of people in each group developed abnormal triglyceride levels over the course of the study? Are these proportions measures of prevalence, incidence, or neither?OphthalmologyOne
One assumption of the test in Problem 10.68 is that the distribution of serum retinol is approximately normal. To verify this assumption, the investigators obtained a frequency distribution of serum
Can the test be implemented based on the data just presented? Why or why not? If yes, implement the test and report a two-tailed p-value?OphthalmologyA 5-year study among 601 participants with
What test can be used to assess whether mean serum retinol has increased over 3 years among subjects in the vitamin A group? OphthalmologyA 5-year study among 601 participants with retinitis
Suppose there is no causal effect of induced abortion on breast cancer. Based on the parity distribution in the two groups, would women with induced abortion be expected to have the same, higher, or
Implement the test in Problem 10.65, and report a two-tailed p-value?CancerA topic of current interest is whether abortion is a risk factor for breast cancer. One issue is whether women who have had
What test can be performed to compare the parity distribution of women with and without induced abortions? CancerA topic of current interest is whether abortion is a risk factor for breast
Implement the method suggested in Problem 10.63, and report a two-tailed p-value?Hospital EpidemiologyDeath of a patient in the hospital is a high-priority medical outcome. Some hospital deaths may
What method of analysis can be used to compare the proportion of adverse events between cases and controls? Hospital EpidemiologyDeath of a patient in the hospital is a high-priority medical
For children with two affected ears, test the hypothesis that responses to the study medications for the first and second ears are independent?
In children with two affected ears at baseline, compare the efficacy of the two study medications, treating the response at 14 days as a graded scale (two cleared ears, one cleared ear, no cleared
For children with one affected ear at baseline, compare the efficacy of the two study medications?
In this problem, act like a detective and look at each risk factor in the data set separately and relate this risk factor to tennis elbow. How you define tennis elbow is somewhat arbitrary. You may
Interpret the results in Problem 10.57 in words?The investigators also assessed clinical outcomes for the patients at 1 year. They defined a favorable outcome as a complete or nearly complete
Perform the test in Problem 10.56, and report a two-sided p-value?The investigators also assessed clinical outcomes for the patients at 1 year. They defined a favorable outcome as a complete or
What test can be performed to assess the association between change in nerve root compression and clinical outcome? The investigators also assessed clinical outcomes for the patients at 1 year.
Interpret the results in Problem 10.54 in words?OrthopedicsA study was performed among subjects with persistent sciatica (El Barzouhi et al. [17]). Sciatica is pain that radiates down the leg and is
Perform the test in Problem 10.53, and report a two sided p-value?OrthopedicsA study was performed among subjects with persistent sciatica (El Barzouhi et al. [17]). Sciatica is pain that radiates
What test can be performed to compare the prevalence of disk herniation between the patients who received surgery vs. the patients who did not receive surgery? OrthopedicsA study was performed
Can you assess the reproducibility of adverse events and negligence designations? Which seems to be more reproducible?Health Services AdministrationIn the Harvard Medical Practice Study [16], a
What will be the expected rates in Problems 10.42 and 10.43 if this level of lack of compliance is realized? Investigators expect that not all participants will comply. In particular, they
Use nonparametric methods to answer Problem 8.71 (p. 326)?Renal DiseaseRefer to the urinary-protein data in Table 8.16 (p. 324).Table 9.16: Relationship of serum estradiol, BMI, and ethnicity in 25
Which nonparametric test should be used to test the hypothesis that the mean SBPs for the two machines are comparable? HypertensionAn instrument that is used in some blood-pressure studies is
What will be the revised sample size estimate in Problem 10.44 if the lack of compliance is taken into account?Investigators expect that not all participants will comply. In particular, they project
Provide a stem-and-leaf plot of the age at first sperm-positive urine specimen?Pediatrics, EndocrinologyA study was performed among 40 boys in a school in Edinburgh to look at the presence of
If we assume that all boys have no sperm cells at age 11 (11.0 years) and all have sperm cells at age 18, then estimate the probability of first developing sperm cells at ages 12 (i.e., between 12.0
Suppose mean age at spermatogenesis = 13.67 years, with standard deviation = 0.89 years and we assume that the age at spermatogenesis follows a normal distribution. The pediatrician would like to
Suppose we are uncertain whether a normal distribution provides a good fit to the distribution of age at spermatogenesis. Answer this question using the results from Problems 10.47ˆ’10.49.
Are frequencies of reporting of adverse events or negligence comparable in review process A (the original review) and review process B (the re-review)? Health Services AdministrationIn the
If the rates in Problems 10.42 and 10.43 are the true rates, how many participants will be needed in each group if a one-sided test with α = .05 is to be used and an 80% chance of finding a
What is the expected event rate in the treated group? Cardiovascular DiseaseA secondary prevention trial of lipid lowering is planned in patients with previous myocardial infarction (MI).
What proportion of controls will have events over 5 years?Cardiovascular DiseaseA secondary prevention trial of lipid lowering is planned in patients with previous myocardial infarction (MI).
Answer Problem 10.40 for biliary secretions?
For all hormone groups except saline, different doses of hormones were administered to different groups of hens. Is there a dose-response relationship between the proportion of hens with increasing
Answer Problem 10.38 for biliary secretions?

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