Questions and Answers of Fundamentals of Biostatistics

Estimate the OR between widowhood and mortality, and provide a 95% CI about this estimate?Mental HealthRefer to Table 10.27.Table 13.27 Use of SAS PROC PHREG to perform conditional logistic
Suppose we wish to perform another study of the association between OC use and MI and will control for age. Set up a logistic regression based on the data in Table 13.7, and use the results to
1. Assess the association between MI and OC use after controlling for age (provide a two-tailed p-value)?2. Estimate the OR between OC use and MI after controlling for age, and provide a 95% CI about
Assess the crude association between MI and OC use without taking age into account (provide a two-tailed p-value)?Cardiovascular DiseaseRefer to Table 13.7.Table 13.7 Association between MI and OC
Compare your results with those obtained using ordinary ANOVA methods based on slopes in Problem 12.49?
Use methods of longitudinal data analysis to compare the rates of change in serum creatinine over time by treatment group?
Suppose we wish to perform another study of the association between MI and severe vertex baldness while controlling for age. We will use a two-sided test with Î± = 0.05 and wish a power
Use logistic regression methods to assess the association between MI and severe vertex baldness while controlling for age. Compare your results to those in Problem 13.95?Cardiovascular DiseaseA study
What is the OR between MI and severe vertex baldness in (i) men ‰¤60 and (ii) men >60? If these are the true ORs, is age an effect modifier of the association between baldness and MI?
Is there a significant association between MI and severe vertex baldness after controlling for age? Please report a two-tailed p-value. Cardiovascular DiseaseA study was performed relating
What is the estimated OR for MI comparing men with severe vertex baldness vs. no baldness after controlling for age? Cardiovascular DiseaseA study was performed relating baldness pattern to MI
What type of study was this? Cardiovascular DiseaseA study was performed relating baldness pattern to MI (heart attack) among men in the Atherosclerosis Risk in Communities (ARIC) study [49].
What is the estimated OR for hypertension comparing Hispanic vs. Caucasian boys with BMI = 25 kg/m2(call this OR3.)? One assumption of the model in Table 13.55 is that the association between
Is BMI an effect modifier of the association between hypertension and ethnic group? Why or why not? One assumption of the model in Table 13.55 is that the association between hypertension and
Suppose the average BMI of Hispanic boys is higher than that for Caucasian boys. Is BMI a confounder of the association between ethnic group and hypertension? If so, is it a positive or negative
What is the estimated OR for hypertension comparing Hispanic boys vs. Caucasian boys based on the results in Table 13.55? (Call this OR2.) Provide a 95% CI for this estimate. What is the difference
What is the estimated OR for hypertension comparing Hispanic boys vs. Caucasian boys? (Call this OR1.) What is a 95% CI for this estimate? HypertensionAn important issue is whether there are
Suppose that 30% of children are obese by the above definition. What percent of hypertension is attributable to obesity? Provide a 95% CI associated with this estimate.HypertensionSuppose that 200
What is the RR for hypertension? What is a 95% CI associated with this estimate?HypertensionSuppose that 200 obese (BMI ≥25) children and 500 normal-weight (BMI <25) children are identified in a
What type of study is this? HypertensionSuppose that 200 obese (BMI ≥25) children and 500 normal-weight (BMI <25) children are identified in a school-based screening for hypertension.
Is pre-existing fracture a confounder in these data?EndocrinologyA study of raloxifene and incidence of fractures was conducted among women with evidence of osteoporosis. The women were initially
Combining both groups, compute the standardized RR for raloxifene vs. placebo and new fractures?EndocrinologyA study of raloxifene and incidence of fractures was conducted among women with evidence
Test the association of study agent with new fractures combining both groups of those with and without preexisting fractures?EndocrinologyA study of raloxifene and incidence of fractures was
Among those with no pre-existing fractures, compute the relative risk of new fractures among those randomized to raloxifene vs. placebo, along with its associated 95% CI?EndocrinologyA study of
Among those with no pre-existing fractures, test whether raloxifene affects the incidence of new fractures?EndocrinologyA study of raloxifene and incidence of fractures was conducted among women with
Compare your results in Problems 13.77 and 13.78?
Repeat the analysis in Problem 13.77 using multipleimputation methods?
Use the complete-case method to relate lead levels in 1972 to full-scale IQ score (variable name IQF), while controlling for age and sex?
How do the results from Problem 13.75 compare with the results in Table 13.51?The hormones in Table 13.51 were also included in the reproducibility study mentioned in Example 13.75 [36]. The
Using the results from Problem 13.74, obtain a measurement-error-corrected OR and 95% CI for each of the hormones?The hormones in Table 13.51 were also included in the reproducibility study mentioned
Provide a 95% CI for the true difference in incidence rates for children with siblings between those with and without a sibling history of ear infection?OtolaryngologyA longitudinal study was
Answer the questions in Problems 13.67 and 13.63 using generalized estimating equation methods, and compare results with the solution to Problems 13.62€“13.63?OtolaryngologyA longitudinal
Compare the percentage of cleared ears between the cefaclor-treated and the amoxicillin-treated groups. Report a two-tailed p-value?OtolaryngologyConsider Data Set EAR.DAT (Table 3.12). Suppose we
1. Compare the percentage of cleared ears among children 2€“5 years of age vs. the percentage of cleared ears among children <2 years of age. Report a two-tailed p-value?2. Compare the
Obtain a point estimate and a 95% CI for the relative risk of breast cancer comparing women whose total fat intake differs by 10 g/day?Cancer, NutritionA logistic-regression analysis similar to that
Use the data for total fat to fit the linear regression of DR total fat intake on FFQ total fat intake. Obtain the regression coefficient, standard error, and p-value from this regression?Cancer,
Using the results from Problems 13.68 and 13.69, obtain an estimate of the RR of breast cancer, comparing women who differ by 10 g/day on total fat intake on the DR, assuming age and alcohol intake
Obtain a 95% CI for the point estimate in Problem 13.70?Cancer, NutritionA logistic-regression analysis similar to that presented in Example 13.73 (on page 743) was run relating breast-cancer
Compare the measurement-error-corrected RR and CI in Problems 13.70 and 13.71 with the uncorrected RR and CI in Problem 13.68?Cancer, NutritionA logistic-regression analysis similar to that presented
Obtain the uncorrected logistic-regression coefficients and standard errors for each of the hormones in Table 13.51?Cancer, EndocrinologyIn the study presented in Example 13.75 (p. 748), other
Obtain the measurement-error-corrected logistic regression coefficient and standard error for each of the hormones in Table 13.51?The hormones in Table 13.51 were also included in the reproducibility
Assess whether a sibling history of ear infection is associated with OTM incidence in the first year of life?OtolaryngologyA longitudinal study was conducted among children in the Greater Boston
1. Suppose we are planning a new study similar in design to study 1. How many participants do we need to study to detect an underlying 3-mm Hg treatment effect for SBP with 80% power assuming there
Assess whether there are any significant treatment or carry-over effects of SBP or DBP in study 1?Three separate two-period cross-over studies were performed, based on different groups of subjects.
Assess whether there are significant carry-over effects for the endpoint in Problem 13.49?
1. Assess whether there are significant treatment effects regarding pain during maximum activity?2. Asses whether there are significant treatment effects regarding pain 12 hours after maximum
Use correlated binary data methods to relate clearance of an ear by 14 days to antibiotic type and age. Use the ear as the unit of analysis?
Consider a subject “cured” if (1) the subject is a unilateral case and the ear clears by 14 days or (2) the subject is a bilateral case and both ears are clear by 14 days. Run a logistic
1. Use logistic-regression methods to assess whether the presence of biliary secretions during the second period is related to dose of hormone used during the second period (do separate analyses for
1. Use logistic-regression methods to assess whether presence of biliary secretions during the second period (any or none) is related to the type of hormone used during the second period?2. Answer
Provide a 95% CI for the estimate in Problem 13.41?Cardiovascular DiseaseSudden death is an important, lethal cardiovascular endpoint. Most previous studies of risk factors for sudden death have
Compute the OR relating the additional risk of sudden death per 100-centiliter (cL) decrease in vital capacity after adjustment for the other risk factors?Cardiovascular DiseaseSudden death is an
What do these statistical tests mean in this instance? Cardiovascular DiseaseSudden death is an important, lethal cardiovascular endpoint. Most previous studies of risk factors for sudden death
Assess the statistical significance of the individual risk factors?Cardiovascular DiseaseSudden death is an important, lethal cardiovascular endpoint. Most previous studies of risk factors for sudden
How much power did the study described in Problem 13.37 have of demonstrating equivalence under the assumptions in Problem 13.36?HypertensionA drug company proposes to introduce a new
Suppose in the actual study that 200 participants are randomized to each group. Forty-four participants who receive drug A and 35 participants who receive current therapy die of CVD in the next 5
Suppose drug A will be considered equivalent to the current therapy if the 5-year CVD mortality is not worse than 20%. How many participants must be enrolled in the study to ensure at least an 80%
Use linear-regression methods to predict the number of episodes of tennis elbow as a function of several risk factors in the same model?
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?
Answer Problem 13.32 for the endpoint of being angina free at 6 months?At the 6-month clinic visit, 61 of 96 patients seen in the PTCA group and 47 of 102 patients seen in the medicaltherapy group
Estimate the RR of MI for patients assigned to PTCA vs. patients assigned to medical therapy, and provide a 95% CI for this estimate?CardiologyA recent study compared the use of percutaneous
Answer the question in Problem 13.29 to assess whether there are differences in efficacy between each pair of antibiotics?
Answer the question in Problem 13.29 to assess whether there are differences in ototoxicity between each pair of antibiotics?
Use methods of meta-analysis to assess whether there are differences in nephrotoxicity between each pair of antibiotics. Obtain point estimates and 95% CIs for the OR, and provide a two-sided p-value?
Estimate the OR relating blood pressure to blood lead, and provide a 95% CI about this estimate?HypertensionA study was conducted in Wales relating blood-pressure and blood-lead levels [46]. It was
Implement the procedure in Problem 13.26, and report a p-value?HypertensionA study was conducted in Wales relating blood-pressure and blood-lead levels [46]. It was reported that 4 of 455 men with
What is an appropriate procedure to test the hypothesis that there is an association between blood pressure and blood lead, while controlling for sex? HypertensionA study was conducted in Wales
Provide a 95% CI for the OR?Table 13.27 Use of SAS PROC PHREG to perform conditional logistic regression on the breast cancer data One assumption in Table 13.46 is that the log odds ratio of
Estimate the OR relating widowhood to mortality based on all the data in Table 10.27?Table 13.27 Use of SAS PROC PHREG to perform conditional logistic regression on the breast cancer data One
Estimate the odds ratio for Group C vs. Group A and provide a 95% CI. Are the results consistent with those in Problem 13.21? Why or why not? One assumption in Table 13.46 is that the log odds
Suppose a cutoff for excessive lifetime acetaminophen intake (L) is a level such that the risk of at least a 30% decline in GFR over 11 years is ‰¥ 10%. What is your best estimate of L?A
Estimate the odds ratio for being a case comparing a subject with a lifetime acetaminophen intake of 1100g vs. a lifetime acetaminophen intake of 100g. Provide a 95% CI for this odds ratio?A logistic
Provide a 95% CI for the OR computed in Problem 13.19?Renal DiseaseA study was performed assessing the association between lifetime analgesic intake and change in estimated glomerular filtration rate
What is the estimated odds ratio for being a case comparing Group D to Group A? Renal DiseaseA study was performed assessing the association between lifetime analgesic intake and change in
Provide a 95% CI for the estimate obtained in Problem 13.17?EndocrinologyA study was performed looking at the risk of fractures in three rural Iowa communities according to whether their drinking
Estimate the OR relating higher calcium and fractures while controlling for age?EndocrinologyA study was performed looking at the risk of fractures in three rural Iowa communities according to
Implement the test in Problem 13.15, and report a p-value (two-sided)?EndocrinologyA study was performed looking at the risk of fractures in three rural Iowa communities according to whether their
Repeat the analyses in Problem 12.67 for the mean change in TBUT at 10 minutes post-instillation vs. baseline?Data from 12.67Use mixed effects methods to compare the mean change in TBUT immediately
Perform the test, and report a p-value (two-tailed)?OrnithologyData are available from four source populations of stonechat birds:(1) An African group that resides year-round in equatorial Africa(2)
Identify which pairs of subspecies are significantly different in mean wing length using a two-sided Bonferroni adjusted Î± level of 0.05?OrnithologyData are available from four source
Write down a model to assess the effects of species and gender in the same model, allowing for the possibility that differences between mean wing lengths of different species vary by gender. What is
For each region, assess whether the change in corneal sensitivity varies by treatment received comparing day 7 vs. day 0 and day 14 vs. day 0, respectively. Use all available data from all 93
Is the treatment effect the same in different regions of the cornea? Ophthalmology, Infectious DiseaseFluoroquinolones are antibiotics used for treating certain types of bacterial infections.
Based on this overall measure of sensitivity, perform a global analysis of the data, as opposed to the region-specific analysis you were asked to perform in Problem 12.86?It may be inefficient to
Use the normal-theory method to test for significant differences in contraceptive-use patterns between the two groups?GynecologyIn a 1985 study of the relationship between contraceptive use and
Use the contingency-table method to perform the test in Problem 13.1?GynecologyIn a 1985 study of the relationship between contraceptive use and infertility, 89 of 283 infertile women, compared with
Use the contingency-table method to perform the test in Problem 13.1?GynecologyIn a 1985 study of the relationship between contraceptive use and infertility, 89 of 283 infertile women, compared with
Compute a 95% CI for the difference in the proportion of women who have ever used IUDs between the infertile and fertile women in Problem 13.1?GynecologyIn a 1985 study of the relationship between
Compute the OR in favor of ever using an IUD for infertile women vs. fertile women?GynecologyIn a 1985 study of the relationship between contraceptive use and infertility, 89 of 283 infertile women,
Provide a 95% CI for the true OR corresponding to your answer to Problem 13.5?GynecologyIn a 1985 study of the relationship between contraceptive use and infertility, 89 of 283 infertile women,
What is the relationship between your answers to Problems 13.2 and 13.6?GynecologyIn a 1985 study of the relationship between contraceptive use and infertility, 89 of 283 infertile women, compared
Refer to Problem 10.30. Estimate the RR for total mortality of the study group vs. the control group. Provide 95% confidence limits for the RR?
Perform a significance test to examine the association between OC use and bacteriuria after controlling for age?Refer to Table 13.8.Risk of bacteriuria among OC users and nonusers % with
Estimate the OR in favor of bacteriuria for OC users vs. non-OC users after controlling for age?Refer to Table 13.8.Risk of bacteriuria among OC users and nonusers % with bacteriuria Non-OC
Provide a 95% CI for the OR estimate in Problem 13.10?Refer to Table 13.8.Risk of bacteriuria among OC users and nonusers % with bacteriuria Non-OC users OC users Age group п 281 1.2 5.6 84
Is the association between bacteriuria and OC use comparable among different age groups? Why or why not?Refer to Table 13.8.Risk of bacteriuria among OC users and nonusers % with bacteriuria
Suppose you did not control for age in the preceding analyses. Calculate the crude (unadjusted for age) odds ratio in favor of bacteriuria for OC users vs. non-OC users?Refer to Table 13.8.Risk of
How do your answers to Problems 13.10 and 13.13 relate to each other? Explain any differences found.Refer to Table 13.8.Risk of bacteriuria among OC users and nonusers % with bacteriuria Non-OC
What test can be used to compare the fracture rates in these two communities while controlling for age? EndocrinologyA study was performed looking at the risk of fractures in three rural Iowa
What test can be used to compare the mean wing length in the four groups?OrnithologyData are available from four source populations of stonechat birds:(1) An African group that resides year-round in

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