hw2 questions – Flashcards
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ecologic comparison
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sometimes called a cross-sectional ecologic study
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cross sectional study allows
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the demonstration of a time sequence between exposure and disease
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controls are needed in a case-control study to
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evaluate whether the frequency of a factor or past exposure among the cases is different from that among comparable persons who do not have the disease under investigation
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mortality from cancer of uterus rises
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with age regardless of whether or not estrogen is used
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case-control studies are among the best observational designs to study diseases of
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low prevalence
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examples of descriptive epidemiologic studies do not usually include
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cohort studies
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what type of study is the lifestyle variable cancer patients study?
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case-control
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does the study have an exposure status variable
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yes, lifestyle
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does this study have a disease status variable
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yes, cancer
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in a case-control study, the odds ratio is used as an estimate of the relative risk
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the exposure in question is rare in the population.
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cohort studies enable the investigator to study cause and effect because the
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temporality of exposure and disease is known
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repeated cross-sectional surveys may
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underestimate past smoking behavior of older age cohorts.
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in cohort studies,
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information can be obtained on rare exposures
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used in cohort studies, the relative risk is a measure
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of the strength of association between a possible risk factor and a disease
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survival curves may be used
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to portray patient's survival in a clinical trial
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failure to account for age cohort effects in smoking prevalence may
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obscure the fact that there had been a shift in the age of onset for lung cancer toward earlier ages.
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a major advantage of cohort studies over case-control studies with respect to the role of a suspected factor is that
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they permit direct estimation of risk of disease in those exposed to the suspected factor
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cohort study is to risk ratio as
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case-control study is to odds ratio
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example of population-based cohort study
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tecumseh, framingham, iowa, all of the above
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nested case-control studies
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use subjects drom a cohort study, provide degree of control, reduce costs, all of the above
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passive follow-up in cohort studies is
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collection and maintenance of data by the federal government
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a clinical trial entails comparing a group of patients treated with a test treatment
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to a comparable group of patients receiving a control treatment
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randomized control community trials
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may be used in special situations such as simple interventions
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controlled clinical trials enable researchers to
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do all of the following
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in contrast to observational studies, intervention studies are employed to test
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the efficacy of prevention measures
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the stanford five-city project, used two types of surveys
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cohort and cross-sectional surveys
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prophylactic trial is designed to
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evaluate the effectiveness of a substance used to prevent disease
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surrogate endpoints in clinical trials may include
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all of the above
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the purpose of a double-blinding in clinical trial is to
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a & b
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phase iii clinical trials for a cancer drug involve
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comparing survival rates for the new drug versus extant therapies.
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the purpose of randomization is
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to reduce errors that resul tofform assignment to study conditions
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major advantage of community trials
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estimate directly the realistic impact of behavior change
