Questions and Answers of Fundamentals of Biostatistics

What is the expected number of otitis-prone families of 100 five-sibling families?Pediatrics, OtolaryngologyOtitis media is a disease that occurs frequently in the first few years of life and is one
Suppose an “otitis-prone family” is defined as one in which at least three siblings of five develop otitis media in the first 6 months of life. What proportion of five-sibling families is otitis
What is the probability that an infant will have one or more episodes of otitis media by the end of the ninth month of life given that no episodes have been observed by the end of the third month of
What is the probability that an infant will have one or more episodes of otitis media by the end of the sixth month of life? The first year of life?Pediatrics, OtolaryngologyOtitis media is a disease
What is the variance of X?One interesting phenomenon of bacteriuria is that there is a “turnover”; that is, if bacteriuria is measured on the same woman at two different points in time, the
What is the mean of X?One interesting phenomenon of bacteriuria is that there is a “turnover”; that is, if bacteriuria is measured on the same woman at two different points in time, the results
What is the probability distribution of X?One interesting phenomenon of bacteriuria is that there is a “turnover”; that is, if bacteriuria is measured on the same woman at two different points in
Suppose 100 women from this population are sampled. What is the probability that 3 or more of them are positive for bacteriuria?Renal DiseaseThe presence of bacteria in a urine sample (bacteriuria)
If a sample size of 5 is selected from this population, what is the probability that 1 or more women are positive for bacteriuria?Renal DiseaseThe presence of bacteria in a urine sample (bacteriuria)
If the preceding 50% rates were each reduced to 40% by a massive education program, then what effect would this change have on the overall mortality rate among true hypertensives; that is, would the
What is the probability that at least 7 of the 10 hypertensives know they have high blood pressure?HypertensionA national study found that treating people appropriately for high blood pressure
What is the probability that among 10 true hypertensives at least 50% are being treated appropriately and are complying with this treatment?HypertensionA national study found that treating people
What is the expected number of siblings in a 2-sibling family who will have 3 or more episodes in the first 2 years of life?An interesting question in pediatrics is whether the tendency for children
What is the probability that neither sibling will have 3 or more episodes in the first 2 years of life?An interesting question in pediatrics is whether the tendency for children to have many episodes
What is the probability that exactly 1 sibling will have 3 or more episodes in the first 2 years of life?An interesting question in pediatrics is whether the tendency for children to have many
What is the probability that 2 siblings will both have 3 or more episodes of otitis media in the first 2 years of life?An interesting question in pediatrics is whether the tendency for children to
Find the probability of not getting any episodes of otitis media in the first year of life.OtolaryngologyAssume the number of episodes per year of otitis media, a common disease of the middle ear in
Find the probability of getting 3 or more episodes of otitis media in the first 2 years of life.OtolaryngologyAssume the number of episodes per year of otitis media, a common disease of the middle
Suppose 10 gonorrhea cases are reported over a 3-month period among 10,000 people living in an urban county. The statewide incidence of gonorrhea is 50 per 100,000 over a 3-month period. Is the
Answer Problem 4.16 for a mixed suburban/rural hospital (hospital E).Infectious DiseaseNewborns were screened for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) in
Answer Problem 4.15 for a mixed suburban/rural hospital (hospital E).Infectious DiseaseNewborns were screened for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) in
Answer Problem 4.14 for a mixed suburban/rural hospital (hospital E).Infectious DiseaseNewborns were screened for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) in
Answer Problem 4.16 for a mixed urban/suburban hospital (hospital C).Infectious DiseaseNewborns were screened for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) in
Answer Problem 4.15 for a mixed urban/suburban hospital (hospital C).Infectious DiseaseNewborns were screened for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) in
Answer Problem 4.14 for a mixed urban/suburban hospital (hospital C).Infectious DiseaseNewborns were screened for human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) in
Answer Problems 4.14 and 4.15 using an approximation rather than an exact probability.Infectious DiseaseNewborns were screened for human immunodeficiency virus (HIV) or acquired immunodeficiency
If 500 newborns are screened at the inner-city hospital, then what is the exact binomial probability of at least 5 HIV-positive test results?Infectious DiseaseNewborns were screened for human
If 500 newborns are screened at the inner-city hospital, then what is the exact binomial probability of exactly 5 HIV-positive test results?Infectious DiseaseNewborns were screened for human
What is the expected value and variance for a Poisson distribution with parameter μ = 4.0?Suppose we want to check the accuracy of self-reported diagnoses of angina by getting further medical
What is the probability of obtaining at least 6 events for a Poisson distribution with parameter μ = 4.0?Suppose we want to check the accuracy of self-reported diagnoses of angina by getting further
What is the probability of obtaining exactly 6 events for a Poisson distribution with parameter μ = 4.0?Suppose we want to check the accuracy of self-reported diagnoses of angina by getting further
What is the expected number of students in the class who will develop influenza?Suppose we want to check the accuracy of self-reported diagnoses of angina by getting further medical records on a
Suppose 6 of 15 students in a grade-school class develop influenza, whereas 20% of grade-school students nationwide develop influenza. Is there evidence of an excessive number of cases in the class?
Evaluate 9!.Suppose we want to check the accuracy of self-reported diagnoses of angina by getting further medical records on a subset of the cases.
EvaluateSuppose we want to check the accuracy of self-reported diagnoses of angina by getting further medical records on a subset of the cases. 10 10 10 10
Answer Problem 4.5 assuming order of selection does not matter.If we have 50 reported cases of angina and we want to select 5 for further review, then how many ways can we select these cases if order
If we have 50 reported cases of angina and we want to select 5 for further review, then how many ways can we select these cases if order of selection matters?Suppose we want to check the accuracy of
What is its cumulative-distribution function?Let X be the random variable representing the number of hypertensive adults in Example 3.12.
What is its variance?Let X be the random variable representing the number of hypertensive adults in Example 3.12.
What is its expected value?Let X be the random variable representing the number of hypertensive adults in Example 3.12.
Derive the probability-mass function for X.Let X be the random variable representing the number of hypertensive adults in Example 3.12.
1. What is the probability that the saliva cotinine level in a mother is elevated during pregnancy if the daughter reports that the mother smoked in-utero? 2. What is the probability that the
If a mother€™s self-report is considered completely accurate, then what is the PVˆ’ of the daughter€™s report? Obstetrics, Health PromotionA study was performed to
If a mother€™s self-report is considered completely accurate, then what is the PV+ of the daughter€™s report, in which positive indicates smoking and negative indicates not
Suppose the reproducibility of the AAI test were improved using better technology. Would the sensitivity of the test increase, decrease, or remain the same? why? Cardiovascular DiseaseThe
What is the specificity of the test?Cardiovascular DiseaseThe ankle-arm blood-pressure index (AAI) is defined as the ratio of ankle systolic blood pressure/arm systolic blood pressure and is used for
If an abnormal ECG as determined by S-T segment depression is regarded as the gold standard for the presence of heart disease and an AAI of < 1.0 is regarded as a possible test criterion for heart
What is another name for the quantity in Problem 3.134?Refer to Problem 3.134,If a subject tests positive on an iPad 2 display, then what is the probability that he(she) will also test positive on
If a subject tests positive on an iPad 2 display, then what is the probability that he(she) will also test positive on the LCD? RadiologyMobile displays have the potential to increase the
If we regard the LCD interpretation as the gold standard, then what is the specificity of the iPad 2 interpretation? RadiologyMobile displays have the potential to increase the flexibility of
If we regard the LCD interpretation as the gold standard, then what is the sensitivity of the iPad 2 interpretation? RadiologyMobile displays have the potential to increase the flexibility of
Suppose that we have 100 women who are age 55 in the year 1995. What is the probability that at least 2 of them will develop breast cancer by 1996? The SEER data is also available for the time
What is the overall % change in 1-year cumulative incidence between period A and period B? The SEER data is also available for the time period 2001–2006 (period B) as shown in Table 3.20.Table
Answer the question in problem 3.128 for the time period 2001–2006?The SEER data is also available for the time period 2001–2006 (period B) as shown in Table 3.20.Table 3.20 Breast cancer 1-year
Suppose that among women who are age 50–74, 22% are age 50–54, 21% are age 55–59, 20% are age 60–64, 19% are age 65–69 and 18% are age 70–74. What is the overall 1-year cumulative
Construct a box plot of the cholesterol changes to the right of the stem-and-leaf plot?Table 2.15: Serum-cholesterol levels (mg/dL) before and after adopting a vegetarian diet*Before €“
Compute the median change in cholesterol?Table 2.15: Serum-cholesterol levels (mg/dL) before and after adopting a vegetarian diet*Before €“ after. Subject Before After Difference* 195 146
Construct a stem-and-leaf plot of the cholesterol changes?Table 2.15: Serum-cholesterol levels (mg/dL) before and after adopting a vegetarian diet*Before €“ after. Subject Before After
Compute the standard deviation of the change in cholesterol levels?Table 2.15: Serum-cholesterol levels (mg/dL) before and after adopting a vegetarian diet*Before €“ after. Subject Before
Compute the mean change in cholesterol?Table 2.15: Serum-cholesterol levels (mg/dL) before and after adopting a vegetarian diet*Before €“ after. Subject Before After Difference* 195 146 49
Suppose the man does not run for 6 months over the winter due to snow on the ground. He resumes running once a week in the spring and records a running time = 12.97 minutes in his first week of
Construct a stem and leaf plot of time_100 using the first 3 most significant digits for the stem and the least significant digit for the leaf. So, for week 1, time_100 = 1280 which has a stem = 128
What is the mean and standard deviation of time_100?Suppose we construct a new variable called time_100 = 100 × time (e.g., for week 1, time_100 = 1280).
What is standard deviation of the 1 mile running time over 18 weeks?Health PromotionA man runs 1 mile approximately once per weekend. He records his time over an 18-week period. The individual times
What is the mean 1 mile running time over 18 weeks?Health PromotionA man runs 1 mile approximately once per weekend. He records his time over an 18-week period. The individual times and summary
Suppose the scale for a data set is changed by multiplying each observation by a positive constant?1. What is the effect on the median?2. What is the effect on the mode?3. What is the effect on the
It is of clinical interest to know if the duration of hospitalization is affected by whether a patient has received antibiotics. Answer this question descriptively using either numeric or graphic
Compute the standard deviation and range for the duration of hospitalization for the 25 patients. TABLE 2.13 Hospltal-stay data First Received Duration First WBC Received bacterial Ser (x 10)
Compute the mean and median for the duration of hospitalization for the 25 patients?Table 2.13: Hospital-stay data First WBC Received Duration First Received bacterial Sex 1 = M 2 = F (x 10°)
In 2015, what proportion of the CHD deaths will occur in women? The investigators reported that for both men and women, inhospital CHD death rates were declining at a rate of 5.3% per year,
What is the expected overall CHD mortality rate in Olmstead County in 2015 if these trends continue? The investigators reported that for both men and women, inhospital CHD death rates were
If 50% of the Olmstead County population is male and 50% is female, what was the overall CHD mortality rate in Olmstead County in 1998? Cardiovascular DiseaseMayo Clinic investigators have
What is the probability of breast cancer among 50- to 59-year-old women in the general population who have a serum-estradiol level of ‰¥ 20 pg/mL? What is another name for this
What is the specificity of this test?CancerBreast cancer is considered largely a hormonal disease. An important hormone in breast-cancer research is estradiol. The data in Table 3.18 on serum
What is the sensitivity of this test?CancerBreast cancer is considered largely a hormonal disease. An important hormone in breast-cancer research is estradiol. The data in Table 3.18 on serum
The area under the ROC curve is 65%. What does it mean? OrthopedicsPiriformis syndrome is a pelvic condition that involves malfunction of the piriformis muscle (a deep buttock muscle), which
The cutoff points of ‰¥ 5 for a VAS test-positive and ‰¤ 4 for a VAS test-negative are arbitrary. Compute and graph the ROC curve for the VAS test by varying the cutoff point for
What is the specificity of the VAS?OrthopedicsPiriformis syndrome is a pelvic condition that involves malfunction of the piriformis muscle (a deep buttock muscle), which often causes back and buttock
What is the sensitivity of the VAS?OrthopedicsPiriformis syndrome is a pelvic condition that involves malfunction of the piriformis muscle (a deep buttock muscle), which often causes back and buttock
Suppose that a baby is born with a birth defect, but the baby’s ancestry is unknown. What is the posterior probability that the baby will have both parents from population A, both parents from
Suppose that in 25% of marriages both people are from population A, in 65% both are from population B, and in 10% there is one partner from population A and one from population B. What is the
In the general population, what is the probability that an individual will have the birth defect, assuming that maternal and paternal genes are inherited independently? GeneticsSuppose a birth
What is the specificity of the CDC algorithm?Infectious Disease, Cardiovascular DiseaseA validation study is to be performed in a local hospital to check the accuracy of assessment of
What is the sensitivity of the CDC algorithm?Infectious Disease, Cardiovascular DiseaseA validation study is to be performed in a local hospital to check the accuracy of assessment of
What is the PV− of the CDC algorithm?Infectious Disease, Cardiovascular DiseaseA validation study is to be performed in a local hospital to check the accuracy of assessment of hospital-acquired
What is the PV+ of the CDC algorithm?Infectious Disease, Cardiovascular DiseaseA validation study is to be performed in a local hospital to check the accuracy of assessment of hospital-acquired
Plot the statistical power versus the true efficacy. Do you think 100 patients is a sufficiently large sample to discover whether the new drug is “significantly better” if the true efficacy of
Repeat the procedure in Problem 3.108 for each simulated patient, assuming the true efficacy of the new antibiotic is(a), 80%,(b) 90%, and(c) 95%, and compute the statistical power for each of (a),
Suppose there is a true probability (true efficacy) of 85% that the new antibiotic will work for an individual patient. Perform a “simulation study” on the computer, based on random number
Suppose you are a genetic counselor and are asked by the parents what the probability is that if they have another (a third) child he or she will be affected by the disease. What is the
What is the probability that the mode of transmission for this particular family is dominant with complete penetrance? Is this a prior probability or a posterior probability? GeneticsA
What is the probability that exactly two of the two offspring will be affected in a family with dominant disease with reduced penetrance? GeneticsA dominantly inherited genetic disease is
What is the probability that exactly two of the two offspring will be affected in a family with dominant disease with complete penetrance? GeneticsA dominantly inherited genetic disease is
Are these proportions prevalence rates, incidence rates, or neither? Do the results in this problem give insight into why the Hispanic paradox occurs (do Hispanic men truly have lower risk of CHD as
What is the expected proportion of Hispanic men who will be identified by health surveys as having a previous heart attack in the past 5 years (who are by definition survivors) if we assume that the
Is the proportion 100 out of 1000 a prevalence rate, an incidence rate, or neither? Cardiovascular DiseaseA fascinating subject of recent interest is the “Hispanic paradox”: Census data
What is the specificity of this test?Cardiovascular DiseaseA fascinating subject of recent interest is the “Hispanic paradox”: Census data “show” that coronary heart disease (CHD) has a lower
What is the sensitivity of this test?To possibly improve on the diagnostic accuracy of the clinical diagnosis for Alzheimer€™s disease, information on both the APOE genotype as well as the
What is the specificity of this test?Mental HealthThe ε4 allele of the gene encoding apolipoprotein E (APOE) is strongly associated with Alzheimer’s disease, but its value in making the diagnosis
If the clinical diagnosis is considered a screening test for Alzheimer’s disease, then what is the sensitivity of this test? Mental HealthThe ε4 allele of the gene encoding apolipoprotein E

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