Questions and Answers of Fundamentals of Biostatistics

Compute a two-sided 95% CI for the true mean serum-creatinine level in Problem 7.3?Renal DiseaseThe mean serum-creatinine level measured in 12 patients 24 hours after they received a newly proposed
How does your answer to Problem 7.4 relate to your answer to Problem 7.3?Renal DiseaseThe mean serum-creatinine level measured in 12 patients 24 hours after they received a newly proposed antibiotic
Suppose (x̅ - μ0) / (s/√n) = -1.52 and a one- sample t test is performed based on seven subjects. What is thaw two-tailed p-values?Renal DiseaseThe mean serum-creatinine level measured
Use a computer program to compute the probability that a t distribution with 36 df exceeds 2.5?Renal DiseaseThe mean serum-creatinine level measured in 12 patients 24 hours after they received a
Use a computer program to compute the lower 10th percentile of a t distribution with 54 df?Renal DiseaseThe mean serum-creatinine level measured in 12 patients 24 hours after they received a newly
Provide a point estimate and 95% CI for the a allele frequency p?Suppose that on a population level it is impossible to genotype large numbers of individuals. However, it is known that among 10,000
Provide a point estimate and 95% CI for the probability of having the PKU phenotype?Suppose that on a population level it is impossible to genotype large numbers of individuals. However, it is known
Suppose the probability of an a allele is p. If people mate randomly, then what is the probability of the (aa) genotype? GeneticsThe estimation of allele probabilities is essential for the
Provide a 95% CI for the sensitivity (two decimal place accuracy is sufficient)?Radiology, CancerA radiologist investigates whether a new (less costly) method for identifying esophageal cancer is as
What is the sensitivity of the test? Radiology, CancerA radiologist investigates whether a new (less costly) method for identifying esophageal cancer is as effective as the gold standard.He
Suppose we want to choose a large enough sample so that the sample mean is within 1 unit of the population mean 99% of the time. What is the minimum sample size to achieve this goal? Suppose we
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
Suppose there is no real change in the patient€™s underlying mean blood pressure regardless of whether she is on medication. What is the probability that she will be put back on
Her doctor is considering taking her off antihypertensive medications but wants to be fairly certain that her €œtrue€ DBP is less than 90 mm Hg. Use a statistical approach to
Provide a 95% CI for the rate of injury to the upper extremity on artificial turf. Express each rate as the number of injuries per 1000 games?Sports MedicineInjuries are common in football and may be
The study reported 45 injuries to the upper extremity on a dry field consisting of artificial turf over the course of 10,112 games. What procedure can be used to assess whether the risk of injury is
Would the person be classified as hypertensive overall based on your answer to Problem 6.100? Why or why not? Explain your answer.A person would be classified as hypertensive overall if his or her
Develop a 95% CI for p based on your answer to Problem 6.99?A person would be classified as hypertensive overall if his or her probability of being hypertensive on an individual day (p) is ≥20%
What proportion of days would the woman be classified as hypertensive based on the preceding data? Another issue the doctor wants to study is what the hypertensive status of the patient usually
Answer the doctor€™s question given the result in Problem 6.97?HypertensionA patient who is taking antihypertensive medication is asked by her doctor to record her blood pressure at home
Provide a 95% CI for true mean SBP for this patient?HypertensionA patient who is taking antihypertensive medication is asked by her doctor to record her blood pressure at home to check that it
1. Answer Problem 6.88 for a binomial distribution with n = 50 and p = .6. 2. Answer Problem 6.89 for a binomial distribution with n = 50 and p = .6. 3. Answer Problem 6.90 for a binomial
1. Answer Problem 6.88 for a binomial distribution with n = 20 and p = .6?2. Answer Problem 6.89 for a binomial distribution with n = 20 and p = .6. 3. Answer Problem 6.90 for a binomial
Do you think that the large-sample binomial confidence limit formula is adequate for this distribution?
What percentage of the CIs include the parameter p?
Using the computer, generate 200 random samples from a binomial distribution with n = 10 and p = .6. Derive a large sample two-sided 90% CI for p based on each sample?
Assess whether there is a relationship between BMD at the femoral shaft and cigarette smoking using CI methodology?
Assess whether there is a relationship between BMD at the femoral neck and cigarette smoking using CI methodology?
Suppose an average of two total cholesterol determinations is to be used as a screening tool to identify children with high cholesterol. The investigators wish to find a value c, such that all
Suppose two total cholesterol determinations are obtained from one child, yielding an average value of 200 mg/dL. What is a two-sided 90% CI for the true mean total cholesterol for that
Determine the actual percent of t-values that exceed 2.776 in absolute value. Do you feel the central-limit theorem is applicable to these data for samples of size 5?S I M U L A T I O NNutritionOn
If the central-limit theorem holds, then what percentage of t-values should exceed 2.776 in absolute value?NutritionOn the computer, draw 1000 bootstrap samples of size 5 from the distribution of 173
What distribution should the t-values follow if the central-limit theorem holds? Assume Î¼0is the population mean for ln(alcoh_dr + 1). S I M U L A T I O NNutritionOn the computer,
Provide a two-sided 95% CI for the probability estimate in Problem 6.79?CancerThe value of mammography as a screening test for breast cancer has been controversial, particularly among young women. A
Suppose a woman is given a mammogram every 2 years starting at age 40. What is the probability that she will have at least one false-positive test result among 5 screening tests during her forties?
Some physicians feel a mammogram is not cost effective unless one can be reasonably certain (e.g., 95% certain) that the false-positive rate is less than 10%. Can you address this issue based on the
What does a false-positive test result mean, in words, in this context?CancerThe value of mammography as a screening test for breast cancer has been controversial, particularly among young women. A
Suppose that there are 4 deaths due to stomach cancer among workers in a tire plant from 1/1/64 to 12/31/83, while 2.5 are expected based on U.S. mortality rates. Provide a 95% CI for the expected
Suppose that there are 6 deaths due to bladder cancer among workers in a tire plant from 1/1/64 to 12/31/83, while 1.8 are expected based on U.S. mortality rates. Provide a 95% CI for the expected
Answer Problem 6.70 for the average heart rate (or blood pressure) over all available levels to baseline?Data Set NIFED.DAT (at www.cengagebrain.com) was described earlier. We wish to look at the
Answer Problem 6.70 for the last available level to baseline?Data Set NIFED.DAT (at www.cengagebrain.com) was described earlier. We wish to look at the effect of each treatment separately on heart
Answer Problem 6.70 for level 3 to baseline?Data Set NIFED.DAT (at www.cengagebrain.com) was described earlier. We wish to look at the effect of each treatment separately on heart rate and systolic
Answer Problem 6.70 for level 2 to baseline?Data Set NIFED.DAT (at www.cengagebrain.com) was described earlier. We wish to look at the effect of each treatment separately on heart rate and systolic
Provide separate point estimates and 95% CIs for the changes in heart rate and SBP (level 1 to baseline) for the subjects randomized to nifedipine and propranolol, respectively. Also provide box
Answer Problem 6.67 for full-scale IQ?We have previously described Data Set LEAD.DAT (at www.cengagebrain.com), in which children were classified according to blood-lead level in 1972 and 1973 by the
Answer Problem 6.67 for performance IQ?We have previously described Data Set LEAD.DAT (at www.cengagebrain.com), in which children were classified according to blood-lead level in 1972 and 1973 by
Compute the mean, standard deviation, standard error, and 95% CI for the mean verbal IQ for children with specific values of the variable lead_grp. Provide a box plot comparing the distribution of
Now suppose we are unwilling to assume a normal distribution for latency time. Re-estimate the probability p that a patient’s latency time will be at least 8 years, and provide a 95% CI for
Still assuming normality, estimate the probability p that a patient’s latency time will be at least 8 years?Infectious DiseaseA cohort of hemophiliacs is followed to elicit information on the
Assuming an underlying normal distribution, compute 95% CIs for the mean and variance of the latency times?Infectious DiseaseA cohort of hemophiliacs is followed to elicit information on the
Answer the question in Problem 6.61 for calorie-adjusted total fat and calorie-adjusted saturated fat?One issue is that people with higher total caloric intake generally have higher intakes of
Compute the large sample and bootstrap 95% CI for mean calorie-adjusted total fat and saturated fat?One issue is that people with higher total caloric intake generally have higher intakes of specific
Compare results from the two methods and comment on whether the large sample method is appropriate for these nutrients?
Compare your results in Problems 6.52 and 6.53 with the actual proportion of sample means that fall in these ranges?ObstetricsFigure 6.4b (p. 172) plotted the sampling distribution of the mean from
Do you feel the central-limit theorem is applicable for samples of size 5 from this population? Explain.ObstetricsFigure 6.4b (p. 172) plotted the sampling distribution of the mean from 200 samples
Obtain descriptive statistics and graphic displays for these salt-taste indices. Do the indices appear to be normally distributed? Why or why not? Compute the sample mean for this index, and obtain
Construct indices measuring responsiveness to sugar taste, and provide descriptive statistics and graphical displays for these indices. Do the indices appear normally distributed? Why or why not?
We want to relate the indices to blood-pressure level. Provide a scatter plot relating mean SBP and mean DBP, respectively, to each of the salt-taste and sugar-taste indices. Does there appear to be
Use interval-estimation methods to determine if the sex of successive births is predictable from the sex of previous births?
Calculate the large sample and bootstrap 95% CI for mean total fat, saturated fat, and alcohol intake based on the diet record from this population. Use 1000 bootstrap samples?
Answer Problem 6.52 for 1 lb rather than 0.5 lb?ObstetricsFigure 6.4b (p. 172) plotted the sampling distribution of the mean from 200 samples of size 5 from the population of 1000 birth-weights given
If the central-limit theorem holds, what proportion of the sample means should fall within 0.5 lb of the population mean (112.0 oz)?ObstetricsFigure 6.4b (p. 172) plotted the sampling distribution of
How do the actual sample results in Problems 6.48 and 6.49 compare?ObstetricsFigure 6.4b (p. 172) plotted the sampling distribution of the mean from 200 samples of size 5 from the population of 1000
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
Select the third point from each of the six samples, and compute the sample sd from the collection of six third points?Table 6.2: Sample of birth-weights (oz) obtained from 1000 consecutive
Compute the standard deviation based on the sample of six means. What is another name for this quantity?Table 6.2: Sample of birth-weights (oz) obtained from 1000 consecutive deliveries at Boston
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
What does a 95% CI mean, in words, in this case?Suppose we decide a better measure of the effectiveness of the drug is the mean decrease in blood pressure rather than the measure of effectiveness
Can we make a statement about the effectiveness of the drug?Suppose we decide a better measure of the effectiveness of the drug is the mean decrease in blood pressure rather than the measure of
What is a 95% CI for the population mean of d?Suppose we decide a better measure of the effectiveness of the drug is the mean decrease in blood pressure rather than the measure of effectiveness used
What is the standard error of d ? Suppose we decide a better measure of the effectiveness of the drug is the mean decrease in blood pressure rather than the measure of effectiveness used
What assumptions have you made to carry out the procedure in Problem 6.41?HypertensionSuppose 100 hypertensive people are given an antihypertensive drug and the drug is effective in 20 of them. By
Suppose we know that 10% of all hypertensive patients who are given a placebo will have their DBP lowered by 10 mm Hg after 1 month. Can we carry out some procedure to be sure we are not simply
What is the best point estimate of the probability p of the drug being effective? HypertensionSuppose 100 hypertensive people are given an antihypertensive drug and the drug is effective in 20
Answer Problem 6.38 for 2.5 log units?Obstetrics, SerologyA new assay is developed to obtain the concentration of M. hominis mycoplasma in the serum of pregnant women. The developers of this assay
Assuming the point estimate in Problem 6.36 is the true population parameter, what is the probability that a particular assay, when expressed in the log scale to the base 2, is no more than 1.5 log
Compute a 95% CI for the variance of the concentrations?Obstetrics, SerologyA new assay is developed to obtain the concentration of M. hominis mycoplasma in the serum of pregnant women. The
Assuming the distribution of concentrations in the log scale to the base 2 is normal, obtain the best estimate of the variance of the concentrations from these data?Obstetrics, SerologyA new assay is
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
Provide a 95% CI for the true incidence rate?Environmental HealthMuch discussion has taken place concerning possible health hazards from exposure to anesthetic gases. In one study conducted in 1972,
What is the best estimate of the 1971 incidence rate from these data?Environmental HealthMuch discussion has taken place concerning possible health hazards from exposure to anesthetic gases. In one
How large a sample would be needed to ensure that the length of the CI in Problem 6.30 is 0.5 μg/mL assuming the sample standard deviation remains at 2.0 μg/mL? PharmacologySuppose we want to
Find a 99% CI for the population variance of the concentrations?PharmacologySuppose we want to estimate the concentration (μg/mL) of a specific dose of ampicillin in the urine after various periods
Find a 95% CI for the population mean concentration?PharmacologySuppose we want to estimate the concentration (μg/mL) of a specific dose of ampicillin in the urine after various periods of time. We
Suppose we know penicillin G at a daily dose of 4.8 megaunits has a 10% failure rate. What can be said in comparing the two drugs?Sexually Transmitted DiseaseSuppose a clinical trial is conducted to
What is a 95% CI for p?Sexually Transmitted DiseaseSuppose a clinical trial is conducted to test the efficacy of a new drug, spectinomycin, for treating gonorrhea in females. Forty-six patients are
What is the best point estimate for p, the probability of a failure with the drug?Sexually Transmitted DiseaseSuppose a clinical trial is conducted to test the efficacy of a new drug, spectinomycin,
If the average SBP for people of comparable age is 130 mm Hg, is there an association between glaucoma and blood pressure?Ophthalmology, HypertensionA study is conducted to test the hypothesis that
Construct a 95% CI for the true mean SBP among people with glaucoma?Ophthalmology, HypertensionA study is conducted to test the hypothesis that people with glaucoma have higher-than-average blood
Do you have any opinion on the physiological and psychological changes in this group of patients? Explain. (Note: A lower score on the PAIS scale indicates worse adjustment to illness.) Renal
Provide a point and interval estimate (95% CI) for the mean of each parameter at baseline and follow-up?Renal DiseaseA study of psychological and physiological health in a cohort of dialysis patients
Are there any advantages to using a common medium versus using different media for performing the susceptibility tests with regard to standardization of results across
Answer Problem 6.20 assuming each laboratory uses a common medium to perform the susceptibility tests?MicrobiologyA nine-laboratory cooperative study was performed to evaluate quality control for
Provide a point and interval estimate (95% CI) for the interlaboratory standard deviation of mean zone diameters for each type of control strain, assuming each laboratory uses different media to
Answer Problem 6.18 assuming each laboratory uses a common medium to perform the susceptibility tests?MicrobiologyA nine-laboratory cooperative study was performed to evaluate quality control for
Provide a point and interval estimate (95% CI) for the mean zone diameter across laboratories for each type of control strain, assuming each laboratory uses different media to perform the
Provide a 95% CI for the percentage of males among patients discharged from Pennsylvania hospitals?Refer to the data in Table 2.13. Regard this hospital as typical of Pennsylvania hospitals.Table
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
What is the best point estimate of the percentage of males among patients discharged from Pennsylvania hospitals?Refer to the data in Table 2.13. Regard this hospital as typical of Pennsylvania
What is the relationship between your answers to Problems 6.12 and 6.13? Refer to the data in Table 2.13. Regard this hospital as typical of Pennsylvania hospitals.Table 2.13: Hospital-stay

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