Questions and Answers of Fundamentals of Biostatistics

Answer Problem 3.95 if the first birth was a live birth?DemographyA study based on data collected from the Medical Birth Registry of Norway looked at fertility rates according to survival outcomes of
What is the probability of 0, 1, and 2+ additional pregnancies if the first birth was a stillbirth? DemographyA study based on data collected from the Medical Birth Registry of Norway looked at
Answer Problem 3.93 if the outcome of the first pregnancy was a live birth?Refer to Problem 3.93,What is the probability of having a live birth (L) at a second birth given that the outcome of the
What is the probability of having a live birth (L) at a second birth given that the outcome of the first pregnancy was a stillbirth (D), that is, death? DemographyA study based on data collected
Calculate the area under the ROC curve. Interpret what this area means in words in the context of this problem?Mental HealthThe Chinese Mini-Mental Status Test (CMMS) consists of 114 items intended
Suppose we want both the sensitivity and specificity to be at least 70%. Use the ROC curve to identify the possible value(s) to use as the cutoff for identifying people with dementia, based on these
Construct an ROC curve based on the table constructed in Problem 3.89?Refer to Problem 3.89,The cutoff value of 20 on the CMMS used to identify people with dementia is arbitrary. Suppose we consider
The cutoff value of 20 on the CMMS used to identify people with dementia is arbitrary. Suppose we consider changing the cutoff. What are the sensitivity and specificity if cutoffs of 5, 10, 15, 20,
What is the specificity of the test?Mental HealthThe Chinese Mini-Mental Status Test (CMMS) consists of 114 items intended to identify people with Alzheimer€™s disease and senile dementia
What is the sensitivity of the test?Mental HealthThe Chinese Mini-Mental Status Test (CMMS) consists of 114 items intended to identify people with Alzheimer€™s disease and senile dementia
Suppose the “cost” of a false negative (2c) is twice that of a false positive (c) (because for a false negative prenatal care would be delayed during the first trimester of pregnancy). If the
What is the PV+ of the test?A drug company is developing a new pregnancy-test kit for use on an outpatient basis. The company uses the pregnancy test on 100 women who are known to be pregnant, for
Based on your answers to Problems 1 and 2, comment on the effect of body position on the levels of systolic and diastolic blood pressure?Table 2.16: Effect of position on blood pressureaSystolic
Construct stem-and-leaf and box plots for the difference scores for each type of blood pressure?Table 2.16: Effect of position on blood pressureaSystolic blood pressurebDiastolic blood pressure Blood
Compute the arithmetic mean and median for the difference in systolic and diastolic blood pressure, respectively, taken in different positions (recumbent minus standing)?Table 2.16: Effect of
Some investigators believe that the effects of diet on cholesterol are more evident in people with high rather than low cholesterol levels. If you split the data in Table 2.15 according to whether
What is the sensitivity of the test?GynecologyA drug company is developing a new pregnancy-test kit for use on an outpatient basis. The company uses the pregnancy test on 100 women who are known to
Another issue in this trial is the possible dependence between ears for the bilateral cases. Comment on this issue based on the data collected?Table 3.12 Format for EAR.DAT Variable Format or code
While controlling for age, propose an analysis comparing the effectiveness of the two antibiotics. Express your results in terms of RR?Table 3.12 Format for EAR.DAT Variable Format or code Column ID
The investigators recorded the ages of the children because they felt this might be an important factor in determining outcome. Were they right? Try to express your results in terms of RR. Table
Does there seem to be any difference in the effect of the antibiotics on clearance of otitis media? Express your results in terms of relative risk (RR). Consider separate analyses for unilateral and
If the population tested is representative of the general population, then what are the PV+ and PVˆ’ using this test? HypertensionLaboratory measures of cardiovascular reactivity are
What is the specificity of automated DBP measurements?HypertensionLaboratory measures of cardiovascular reactivity are receiving increasing attention. Much of the expanded interest is based on the
If the manual measurements are regarded as the €œtrue€ measure of reactivity, then what is the sensitivity of automated DBP measurements? HypertensionLaboratory measures of
Compute the PV− under these altered assumptions. How does the true PV− using a screening criterion of SCN ≥ 100 μg/mL for identifying smokers compare with the PV− based on self-reports
Assuming the percentage of students with SCN ≥ 100 μg/mL in these two subgroups is the same as in those who truly report 1–4 and 5–14 cigarettes per week, compute the specificity under these
What is the PVˆ’ of the test?Suppose the self-reports are completely accurate and are representative of the number of eighth-grade students who smoke in the general community. We are
What is the PV+ of the test?Suppose the self-reports are completely accurate and are representative of the number of eighth-grade students who smoke in the general community. We are considering using
What is the specificity of the test?Suppose the self-reports are completely accurate and are representative of the number of eighth-grade students who smoke in the general community. We are
What is the sensitivity of the test for heavy-smoking students (students who smoke ‰¥ 45 cigarettes per week)? Suppose the self-reports are completely accurate and are representative of
What is the sensitivity of the test for moderate-smoking students (students who smoke 15€“44 cigarettes per week)? Suppose the self-reports are completely accurate and are
What is the sensitivity of the test for light-smoking students (students who smoke ‰¤ 14 cigarettes per week)? Suppose the self-reports are completely accurate and are representative
What is another name for this quantity?Suppose it is estimated based on a large sample of births in California that 20% of mothers smoke at the time of delivery.Suppose the screening test for
What is the probability that a mother smokes at the time of delivery if the dried blood specimen is ≥ 5 ng/mL? Suppose it is estimated based on a large sample of births in California that 20%
What is the specificity using this cut-point?Genetics, ObstetricsPrecise quantification of smoking during pregnancy is difficult in retrospective studies. Routinely collected blood specimens from
What is the sensitivity using this cut-point?Genetics, ObstetricsPrecise quantification of smoking during pregnancy is difficult in retrospective studies. Routinely collected blood specimens from
Are the child’s asthma status and the mother’s smoking status independent? Why or why not?Suppose, alternatively, that if the father is a current smoker, then the probability that the mother is a
Are the child’s asthma status and the father’s smoking status independent? Why or why not?Suppose, alternatively, that if the father is a current smoker, then the probability that the mother is a
Answer Problem 3.59 if the child does not have asthma?Suppose, alternatively, that if the father is a current smoker, then the probability that the mother is a current smoker is .6; whereas if the
Answer Problem 3.58 if the child does not have asthma?Suppose, alternatively, that if the father is a current smoker, then the probability that the mother is a current smoker is .6; whereas if the
What is the posterior probability that the mother is a current smoker if the child has asthma? Suppose, alternatively, that if the father is a current smoker, then the probability that the
Suppose a child has asthma. What is the posterior probability that the father is a current smoker? Suppose, alternatively, that if the father is a current smoker, then the probability that the
Under the assumptions made in Problems 3.55 and 3.56, find the unconditional probability that the offspring will have asthma?Suppose, alternatively, that if the father is a current smoker, then the
Are the current smoking habits of the father and the mother independent? Why or why not? Suppose, alternatively, that if the father is a current smoker, then the probability that the mother is a
If the probability that the father is a current smoker is .5, what is the probability that the father is a current smoker and that the mother is not a current smoker? Suppose, alternatively,
Consider the subgroup of families in which the mother is not a current smoker. What is the probability that the father is a current smoker among such families? How does this probability differ from
Suppose the smoking habits of the parents are independent and the probability that the mother is a current smoker is .4, whereas the probability that the father is a current smoker is .5. What is the
What is the probability of having a length of gestation ≤ 36 weeks given that an infant is low birth-weight? ObstetricsThe following data are derived from the Monthly Vital Statistics Report
Show that the events {length of gestation ≤ 31 weeks} and {low birthweight} are not independent?ObstetricsThe following data are derived from the Monthly Vital Statistics Report (October 1999)
What is the probability of having a low birth-weight infant? ObstetricsThe following data are derived from the Monthly Vital Statistics Report (October 1999) issued by the National Center for
Answer Problem 3.48 where only the male sibling is affected?Suppose that in a family with two male siblings, both siblings are affected with a genetically inherited disease. Suppose also that,
Answer Problem 3.46 for a family with one male and one female sibling in which both siblings are affected?Suppose that in a family with two male siblings, both siblings are affected with a
Answer Problem 3.46 for a family with two male siblings in which only one sibling is affected?Suppose that in a family with two male siblings, both siblings are affected with a genetically inherited
Assume that the dominant, recessive, and sex-linked modes of inheritance follow the probability laws given in Problems 3.32, 3.37, and 3.40 and that, without prior knowledge about the family in
Answer Problem 3.42 for families with two male siblings?Suppose that a disease is inherited via a sex-linked mode of inheritance. The implications of this mode of inheritance are that each male
Answer Problem 3.41 for families with two male siblings?Suppose that a disease is inherited via a sex-linked mode of inheritance. The implications of this mode of inheritance are that each male
Answer Problem 3.40 for families with two male siblings?Suppose that a disease is inherited via a sex-linked mode of inheritance. The implications of this mode of inheritance are that each male
What is the probability that neither sibling is affected?Suppose that a disease is inherited via a sex-linked mode of inheritance. The implications of this mode of inheritance are that each male
What is the probability that exactly one sibling is affected?Suppose that a disease is inherited via a sex-linked mode of inheritance. The implications of this mode of inheritance are that each male
In a family with one male and one female sibling, what is the probability that both siblings are affected? Suppose that a disease is inherited via a sex-linked mode of inheritance. The
What is the probability that neither sibling is affected? Suppose that a disease is inherited via an autosomal recessive mode of inheritance. The implications of this mode of inheritance are
What is the probability that exactly one sibling is affected? Suppose that a disease is inherited via an autosomal recessive mode of inheritance. The implications of this mode of inheritance are
What is the probability that in a family with two children, both siblings are affected? Suppose that a disease is inherited via an autosomal recessive mode of inheritance. The implications of
If A, B are two events such that A = {older child is affected}, B = {younger child is affected}, then are the events A, B independent? GeneticsSuppose that a disease is inherited via a dominant
Suppose the older child is affected. What is the probability that the younger child is affected? GeneticsSuppose that a disease is inherited via a dominant mode of inheritance and that only one
What is the probability that neither sibling is affected? GeneticsSuppose that a disease is inherited via a dominant mode of inheritance and that only one of the two parents is affected with the
What is the probability that exactly one sibling is affected?GeneticsSuppose that a disease is inherited via a dominant mode of inheritance and that only one of the two parents is affected with the
What is the probability that in a family with two children, both siblings are affected? GeneticsSuppose that a disease is inherited via a dominant mode of inheritance and that only one of the
Suppose we identify a 5€“8-year-old child with influenza in the village but are uncertain whether the child was vaccinated. If we make the same assumptions as in Problems
What % of 5€“8-year-old children in the village will get influenza? Suppose that 80% of 3€“4-year-old children and 70% of 5€“8-year-old children in a village are
What % of 3€“4-year-old children in the village will get influenza? Suppose that 80% of 3€“4-year-old children and 70% of 5€“8-year-old children in a village are
Suppose 3 children in a village ages 3, 5, and 7 are vaccinated with the QIV vaccine. What is the probability that at least one child among the 3 will get influenza? Infectious DiseaseCommonly
Assuming there are 1000 people 65+ years of age in the community, what is the expected number of cases of Alzheimer€™s disease in the community? Suppose a study of
What is the expected overall prevalence of Alzheimer€™s disease in the community if the prevalence estimates in Table 3.5 for specific age€“gender groups hold? Suppose a
What is the probability that at least one member of the couple is affected? Suppose the probability that both members of a married couple, each of whom is 75€“79 years of age, will
What is the conditional probability that the woman will be affected given that the man is affected? How does this value compare with the prevalence in Table 3.5? Why should it be the same (or
What is the conditional probability that the man will be affected given that the woman is affected? How does this value compare with the prevalence in Table 3.5? Why should it be the same (or
Suppose we know two of the three people have Alzheimer€™s disease. What is the conditional probability that they are both younger than 80 years of age? Mental HealthEstimates of the
Suppose we know two of the three people have Alzheimer€™s disease. What is the conditional probability that they are both women? Mental HealthEstimates of the prevalence of
Suppose we know one of the three people has Alzheimer€™s disease, but we don€™t know which one. What is the conditional probability that the affected person is a
What is the probability that exactly one of the three people has Alzheimer€™s disease? Mental HealthEstimates of the prevalence of Alzheimer€™s disease have recently been
What is the probability that at least one of the three people has Alzheimer€™s disease? Mental HealthEstimates of the prevalence of Alzheimer€™s disease have recently been
What is the probability that at least one of the women has Alzheimer€™s disease? Mental HealthEstimates of the prevalence of Alzheimer€™s disease have recently been provided
What is the probability that all three of these individuals have Alzheimer€™s disease? Mental HealthEstimates of the prevalence of Alzheimer€™s disease have recently been
Based on Problem 3.12, what is the conditional probability that the father has influenza given that the mother does not have influenza? Suppose an influenza epidemic strikes a city. In 10% of
Based on Problem 3.12, what is the conditional probability that the father has influenza given that the mother has influenza? Suppose an influenza epidemic strikes a city. In 10% of families the
What is the probability that at least one child will get influenza? Suppose an influenza epidemic strikes a city. In 10% of families the mother has influenza; in 10% of families the father has
Are the events A1 = {mother has influenza} and A2 = {father has influenza} independent? Suppose an influenza epidemic strikes a city. In 10% of families the mother has influenza; in 10% of
Represent D in terms of B and C?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second
Represent C in terms of A1, A2, A3, and A4?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza},
What does A2 mean?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second child has
What does A1 mean?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second child has
Express D in terms of B and C?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second
Express C in terms of A1, A2, A3, and A4?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4
What does A3 ∩ B mean?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second child
What does A3 ∪ B mean?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second child
Are A3 and A4 mutually exclusive?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 =
What does A1 ∩ A2 mean?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second child
What does A1 ∪ A2 mean?Consider a family with a mother, father, and two children. Let A1 = {mother has influenza}, A2 = {father has influenza}, A3 = {first child has influenza}, A4 = {second child
Based on the box plot, does the arithmetic mean or the geometric mean provide a more appropriate measure of location for this type of data?

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