Questions and Answers of Fundamentals of Biostatistics

A reasonable summary of the data might be provided by relating the score Si given by Si = 1 if never, Si = 2 if irregular, Si = 3 if fall and winter, and Si = 4 if whole year. What method can be used
Suppose we specifically wish to compare women who used cod liver oil for the entire year during childhood vs. women who never used it.(i) Perform this comparison using the LSD method, and report a
Table 12.47 is the ANOVA table. Table 12.47: ANOVA table of effect of cod liver oil intake during childhood on BMD Nutrition, EndocrinologyA study was performed to relate aspects of
We wish to use a one-way ANOVA model to compare the means of the four groups. Should we use a fixed effects or random-effects model, and why? Nutrition, EndocrinologyA study was performed to
What is the coefficient of variation for TBUT as estimated from these data?OphthalmologyData were collected on TBUT, a measure of how long it takes for tears to form. This is a commonly used measure
What is the intraclass correlation coefficient for (TBUT) for these data? What does it mean? OphthalmologyData were collected on TBUT, a measure of how long it takes for tears to form. This is a
Fit this model to the above data and report the p-value for the overall F test?OphthalmologyData were collected on TBUT, a measure of how long it takes for tears to form. This is a commonly used
What is a reasonable type of model to fit these data? Write out the model, and explain what the terms mean?OphthalmologyData were collected on TBUT, a measure of how long it takes for tears to form.
Use the FDR method to correct for multiple comparisons using an FDR = .05. Which SNPs show statistically significant effects? How do the results compare with those in Problem 12.72? Genetics,
Use the Bonferroni method to correct for multiple comparisons. Which SNPs show statistically significant effects? Genetics, DiabetesSuppose we have separately analyzed the effects of 10 SNPs
What are your overall conclusions concerning the effects of non blink time period on change in TBUT?
Repeat the analyses in Problem 12.67 for the mean change in TBUT at 15 minutes post-instillation vs. baseline?Data from 12.67Use mixed effects methods to compare the mean change in TBUT immediately
Repeat the analyses in Problem 12.67 for the mean change in TBUT at 5 minutes post-instillation vs. baseline?Data from 12.67Use mixed effects methods to compare the mean change in TBUT immediately
Use mixed effects methods to compare the mean change in TBUT immediately post-instillation against baseline according to participant (1, 2, . . . , 14) and nonblink time period (3 sec vs. 6 sec vs.
Are there significant interaction effects between simvastatin-niacin and antioxidants? What does an interaction effect mean in the context of this trial? Cardiovascular DiseaseA randomized trial
Using the LSD method, identify which pairs of groups are significantly different?Cardiovascular DiseaseA randomized trial examined the effects of lipid-modifying therapy (simvastatin plus niacin) and
Perform a one-way ANOVA to assess whether there are significant differences in mean change in percent stenosis among the four groups?Cardiovascular DiseaseA randomized trial examined the effects of
Summarize the findings in a few sentences, and compare them with the results in Problem 12.62?HypertensionRefer to Table 12.16 (on page 595). A similar ANCOVA was performed using PROC GLM of SAS
Summarize the findings in a few sentences?HypertensionRefer to Table 12.15 (on page 593). A similar two-way ANOVA was run using PROC GLM of SAS comparing mean diastolic blood pressure (DBP) by study
Analyze the data regarding the sunlight hypothesis, and summarize your findings?Cardiovascular DiseaseA study was conducted to assess the effect of atorvastatin with or without an antibody to serum
What is the two-sided p-value associated with the test statistic in Problem 12.59?Cardiovascular DiseaseA study was conducted to assess the effect of atorvastatin with or without an antibody to serum
What is the test statistic to perform the test in Problem 12.56 based on the data in Table 12.40?Cardiovascular DiseaseA study was conducted to assess the effect of atorvastatin with or without an
What is your best estimate of the variance of HDL cholesterol within a treatment group?Cardiovascular DiseaseA study was conducted to assess the effect of atorvastatin with or without an antibody to
State the hypotheses to be tested?Cardiovascular DiseaseA study was conducted to assess the effect of atorvastatin with or without an antibody to serum protein convertase subtilisin/kexin (PSCSK9) in
What test can be used to assess whether there are overall differences in mean HDL cholesterol among the three treatment groups? Cardiovascular DiseaseA study was conducted to assess the effect
Use nonparametric methods to compare MAXFWT among the three exposure groups defined by the variable LEAD_GRP?
Answer Problem 12.44 for IQF (full-scale IQ)?
Compare your results in Problems 12.44 and 12.45 with the corresponding results in Table 12.9 (on page 582) for MAXFWT and Problem 12.40 for IQF where parametric methods were used. Table 12.9:
Use ANOVA methods to compare the mean change in serum-creatinine values from the baseline visit to the 1978 visit among women in the high-NAPAP group, low-NAPAP group, and the control group?
1. Fit a regression line relating serum creatinine to time for each person in each of the high-NAPAP group, the low-NAPAP group, and the control group. How do you interpret the slope and intercept
Compute the intra-class correlation coefficient between replicate plasma beta-carotene blood samples at baseline. Provide a 95% CI about this estimate. Perform the analysis based on the entire data
1. Use linear-regression methods to assess whether plasma-carotene levels increase over the 12-week period. Use appropriate data transformations if necessary. Perform separate analyses for each of
Estimate the intra-class correlation for each of plasma estrone, plasma and rostenedione, and plasma testosterone, and provide associated 95% confidence limits. Is the reproducibility of these
Perform the test mentioned in Problem 12.42, and report a p-value. How do your results compare with a parametric analysis of the data?GastroenterologyIn Table 12.39, we present data relating protein
If we do not want to assume normality for these distributions, then what statistical procedure can be used to compare the three groups? GastroenterologyIn Table 12.39, we present data relating
Determine a 95% CI for the underlying mean difference in full-scale IQ for each pair of groups considered?Table 12.38: Format of TEMPERAT.DAT Column Comment (mo/da/yr) (°F) (1-20) (°F) 1.
Use ANOVA methods to assess whether there are any overall differences between the control group, the currently exposed group, and the previously exposed group in mean full-scale IQ. Also, compare
Assume a fixed-effects model. Use the method of multiple comparisons to assess which specific locations in the house are different in mean temperature?
Are there significant differences in temperature between different locations in the house?
Assume a random-effects model. Estimate the between-day vs. within-day variation in temperature within this house?
Estimate the CV for each of the hormones in Problem 12.35?Table 12.37: Format of ENDOCRIN.DAT Column Units Subject number Replicate number Plasma estrone 3 5-8 pg/mL pg/mL ng/dL ng/dL Plasma
Estimate the between-subject and within-subject variation for plasma estrone, plasma androstenedione, and plasma testosterone?Table 12.37: Format of ENDOCRIN.DAT Column Units Subject number
Which methodology do you think is more appropriate in Problem 12.33?EndocrinologyA study was conducted [15] concerning the effect of calcium supplementation on bone loss among postmenopausal women.
Identify which pairs of groups are different from each other, using both t tests and the method of multiple comparisons. Report a p-value for each pair of treatment groups?EndocrinologyA study was
Implement the test in Problem 12.31, and report a p-value?EndocrinologyA study was conducted [15] concerning the effect of calcium supplementation on bone loss among postmenopausal women. Women were
What test can be used to compare the mean rate of bone loss in the three groups? EndocrinologyA study was conducted [15] concerning the effect of calcium supplementation on bone loss among
1. Use ANOVA methods to test whether the change in biliary-secretion levels is comparable for the five hormone groups. Identify and test for any specific group differences?2. Answer Problem 12.27 for
Perform a two-way ANOVA to jointly assess the effects of preparation and follow-up time on plasma-carotene levels. Is there any evidence that the effect of preparation differs by time period?Table
1. Is there a significant difference in bioavailability of the four different preparations? Use ANOVA methods to assess this based on the 6-week data in comparison with baseline?2. Use the methods in
Use ANOVA methods to estimate the CV for plasma beta-carotene for the 23 participants, based on the two baseline measurements?Table 12.35: Format of BETACAR.DAT Code Variable Column Preparation
Is there a difference in underlying mean blood pressure by day for this participant? HypertensionAn instructor in health education wants to familiarize her students with the measurement of blood
Estimate the between-day and within-day components of variance for this participant?HypertensionAn instructor in health education wants to familiarize her students with the measurement of blood
Test the hypothesis that mean change in DBP is the same among the four groups?HypertensionSome common strategies for treating hypertensive patients by nonpharmacologic methods include (1) weight
Analyze whether meditation instruction has a significant effect on reducing blood pressure?HypertensionSome common strategies for treating hypertensive patients by nonpharmacologic methods include
Analyze whether counseling for weight reduction has a significant effect on reducing blood pressure?HypertensionSome common strategies for treating hypertensive patients by nonpharmacologic methods
Test the hypothesis that mean change in DBP is the same among the four groups?HypertensionSome common strategies for treating hypertensive patients by nonpharmacologic methods include (1) weight
Perform the test mentioned in Problem 12.12, and report appropriate p-values identifying differences between specific groups?Mental HealthFor the purpose of identifying older non demented people with
What test procedure can be used to test for significant differences among the groups? Mental HealthFor the purpose of identifying older non demented people with early signs of senile dementia, a
Estimate the proportion of the variance attributable to between-machine vs. within-machine variability?HypertensionAutomated blood-pressure measuring devices have appeared in many banks, drugstores,
Test whether the mean difference is consistent over all four locations?HypertensionAutomated blood-pressure measuring devices have appeared in many banks, drugstores, and other public places. A study
Is a fixed-effects or a random-effects ANOVA appropriate here? HypertensionAutomated blood-pressure measuring devices have appeared in many banks, drugstores, and other public places. A study
Compare the means of each pair of groups using the Bonferroni method?Pulmonary DiseaseTwenty-two young asthmatic volunteers were studied to assess the short-term effects of sulfur dioxide (SO2)
Compare the means of each pair of groups using the LSD method?Pulmonary DiseaseTwenty-two young asthmatic volunteers were studied to assess the short-term effects of sulfur dioxide (SO2) exposure
Test the hypothesis that there is an overall mean difference in bronchial reactivity among the three lung-function groups?Pulmonary DiseaseTwenty-two young asthmatic volunteers were studied to assess
Using the data in Table 12.29, perform a multiple comparisons procedure to identify which specific underlying means are different?NutritionResearchers compared protein intake among three groups of
Suppose that in the general population, 70% of vegetarians are lacto-ovo-vegetarians, whereas 30% are strict vegetarians. Perform a statistical procedure to test whether the contrast L = 0.7
Compare the means of each specific pair of groups using the LSD methodology?NutritionResearchers compared protein intake among three groups of postmenopausal women: (1) women eating a standard
What is the p-value from the test performed in Problem 12.1? NutritionResearchers compared protein intake among three groups of postmenopausal women: (1) women eating a standard American diet
Perform a statistical procedure to compare the means of the three groups using the critical-value method?NutritionResearchers compared protein intake among three groups of postmenopausal women: (1)
Provide a 95% confidence interval for the true Spearman rank correlation (ρs)?The distribution of dietary intake for individual food items is often not very normally distributed.An alternative
Test the hypothesis that the Spearman rank correlation is significantly different from 0 [provide a p-value (two-tailed)]?The distribution of dietary intake for individual food items is often not
Provide a 95% confidence interval for Ï?NutritionThe assessment of diet is an important exposure for many disease outcomes. However, there is often much imprecision in dietary recall. In
Test the hypothesis that the true Pearson correlation (Ï) is significantly different from zero [provide a p-value (two-tailed)]?NutritionThe assessment of diet is an important exposure for
What is the estimated mean FEV for a nonsmoking 15-year-old boy with height = 5€™6€ (66 inches)? There was some previous literature that the effect of age and height on FEV
What is the estimated mean change in SBP for an average patient taking 2000 mg of Bosentan? Provide a 95% confidence interval corresponding to this estimate.HypertensionEndothelin is a powerful
What does the intercept mean in this context? What is the estimated % decline in visual field per year?OphthalmologyRetinitis pigmentosa (RP) is a hereditary ocular disease in which patches of
What is the estimated visual field for this subject after 20 years of follow-up? Provide a 95% confidence interval associated with this estimate.OphthalmologyRetinitis pigmentosa (RP) is a hereditary
If the corrected sum of cross products (Lxy) is 0.744, estimate the slope in the regression of CFR(y) on MVR(x)?CardiologyCoronary flow reserve (CFR) was estimated in 31 patients with hypertension.
Estimate the intercept of this regression line?CardiologyCoronary flow reserve (CFR) was estimated in 31 patients with hypertension. Investigators measured the myocardial velocity ratio (MVR)
Test whether there is a significant relation between these two variables at the 5% level?CardiologyCoronary flow reserve (CFR) was estimated in 31 patients with hypertension. Investigators measured
What is the residual variance around the regression line? CardiologyCoronary flow reserve (CFR) was estimated in 31 patients with hypertension. Investigators measured the myocardial velocity
What is the value of adjusted R2for this line? How do you interpret it? CardiologyCoronary flow reserve (CFR) was estimated in 31 patients with hypertension. Investigators measured the
Test whether this correlation coefficient is significantly different from 0, and report a p-value (two-tailed)?
Provide a 95% Cl for the true correlation coefficient?
The regression coefficient for smoking is 0.7 ± 0.1, p < .001. Does this mean that smokers have higher pulmonary function than nonsmokers? Why or why not?Table 11.31: FEV.DOC Some
What does the regression coefficient for smoking mean in Table 11.34? How does it differ from the regression coefficient in Table 11.33? It is well known that age, height, and sex are important
Is there evidence of non linearity for age or for height? There was some previous literature that the effect of age and height on FEV might not be linear. Hence, we ran the regression model in
Fit the regression line using the method of least squares, and assess whether there is a significant change in visual field over time for this subject. Report a two-sided
Write down a linear regression model that summarizes this relationship?OphthalmologyRetinitis pigmentosa (RP) is a hereditary ocular disease in which patches of pigment appear on the retina,
1. Perform the analysis just suggested for weight. Is there a significant association between the rate of growth (b) and mean HgbA1c (h)? 2. Repeat the analysis in Problem 11.100 for height?3.
It is well known that African American women have higher levels of obesity than Caucasian women. Are there differences between estradiol levels for African American women and Caucasian women after
Do the relationships between the adiposity measures and serum estradiol persist after controlling for the other breast-cancer risk factors in list items 1 to 6?
Are these relationships similar for Caucasian and African American women?
Is there a crude association between either measure of adiposity (BMI, WHR), considered separately, and serum estradiol?
Compute a rank correlation between change in weight and change in HgbA1c, each over 1 year. Use this measure to directly test the hypothesis that change in weight over 1 year is related to change in
Do the results in Problem 11.93 imply a relationship between change in HgbA1c and change in weight for an individual boy? Why or why not? DiabetesA group of 10-year-old boys were first
Please perform the test in Problem 11.92, and report a two-tailed p-value?DiabetesA group of 10-year-old boys were first ascertained in a camp for diabetic boys. They had their weight measured at
What test can be performed to assess the relationship between weight and HgbA1c at the initial visit?DiabetesA group of 10-year-old boys were first ascertained in a camp for diabetic boys. They had
Based on your answers to Problems 11.89 and 11.90, make a projection of the incidence rate of diabetes mellitus during the period 1995ˆ’1999, and provide a 95% confidence interval about
Test for whether there has been a significant change in diabetes incidence over time?DiabetesThe Mayo Clinic is based in Rochester, Minnesota. Residents of Rochester and surrounding areas get almost

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