Epidemiology final
Over the years, some definitions of "cause" have included which of the following?
"that which produces," "an event that preceded the disease onset" "something that makes a difference."
Which of the following study designs are considered observational studies?
- Cohort, cross-sectional, case-control, ecological
"Place" is an important aspect of disease distribution because it includes aspects of what? Select all that apply.
- Physical environment - Biological environment - Social environment
Describing disease by person, place, and time is done for what kind of purposes?
- Scientific - Administrative
If you wanted to find data on cancer incidence in the United States, which would be a likely source of this information?
- Surveillance, Epidemiology and End Results Systems (SEERS)
Epidemiologic surveillance includes which of the following?
- Systematic collection of data - Analysis of data - Dissemination of data
What causes the "ecologic fallacy"?
- The lack of information at the individual level
Data from the U.S. Census are used:
- To assign members of the House of Representatives to the states and to identify denominators for incidence and prevalence measures.
Important reasons to conduct surveillance on a regular basis include:
- To establish a baseline for the community - To identify an outbreak in the community - To monitor disease trends
Determinants of disease include:
- causes of disease - preventative factors - genetic make up
Which of the following measures can be estimated from a clinical trial?
- cumulative incidence, risk difference and risk ratio
Records on births, deaths, marriages, and divorces have been collected since 1933.
- false (Records on births and deaths have been collected since 1933, but some states still do not collect information on marriages and divorces)
Which statements are true about controls in a case-control study?
-They must represent the source population, from which cases arose. -They are also called the "referent group." -They should represent the exposure distribution in the source population. -They must be sampled independently of exposure status.
In a population of 5,000 people, 100 ate spinach contaminated with E. coli (O157:H7) and became ill. Of the ill, 15 died. What was the case fatality rate?
150 per 1000
Unless resources are unlimited, the optimum ratio of cases to controls is:
1:4
A worldwide epidemic is referred to as:
A pandemic
Selection bias is more common in what kind of studies?
All
Health risk behaviors of adults in the U.S. are assessed through the:
Behavioral Risk Factor Surveillance System
What is the term for a systematic error that is introduced in the study design or the way it is conducted?
Bias
An exposure-response curve is related to which of Hill's criteria?
Biological gradient
When the International Classification of Disease (ICD) is revised, deaths from a specific cause tend to:
Cannot tell without knowing more
Self-selection bias in a case-control study may occur if refusal or nonresponse is related to:
Case and exposure status
Which of the following study designs begin with people who have a disease?
Case control, therapeutic trial
Recall bias can occur in any study design, but it is most common in:
Case-control studies
Which study type is the typical design for measuring incidence?
Cohort
The Newburgh-Kingston Fluoride Study increased fluoride levels in the water of residents living in the community of Newburgh, NY, in order to see if this intervention would reduce dental caries. This is an example of what kind of experimental study?
Community trial
From the following, choose one way to evaluate a screening program.
Compare screened and unscreened populations
Which control group is most comparable to the exposed group in a cohort study?
Comparison
The Healthy Worker Effect can be minimized by selecting which type of control group?
Comparison cohort
Which of the following should be considered as an alternative explanations for the results of a study
Confounding bias, random error
The type of confounding that can occur when participants are given a treatment for a specific disease that might be related to the outcome is called:
Confounding by indication
The type of confounding that occurs when the severity of disease is a confounder between the treatment and outcome is called:
Confounding by severity
Trials in which all participants receive all the treatments, at different times, are referred to as:
Cross over trials
Which study design is most often used for public health planning?
Cross sectional
The percentage of freshman girls who become pregnant over the course of their high school years. This measure of disease frequency is:
Cumulative incidence
Consider the definition of epidemiology—"the study of the distribution and determinants of disease frequency in human populations and the application of this study to control health problems." Which part of this definition is the "domain" of descriptive epidemiology?
Distribution of disease
What is a common problem of ecologic studies?
Ecologic fallacy
Which of the following is not a strength of case-control studies?
Efficient for studying rare exposures
If there is no relationship between exposure and disease, then the relative measure would be:
Equal to 1.0
Match each era with its causal paradigm.
Era of chronic disease epidemiology: Web of causation Era of infectious disease epidemiology: Causes, consequences, prevention and treatment of diseases Era of sanitary reform: Miasmatic causes of disease Emergent era: Eco-epidemiology and globalism
Arrange the eras of epidemiology into the correct chronological order.
Era of infectious disease epidemiology: Early 1900s Era of sanitary reform: Late 1800s Era of chronic disease epidemiology: Late 1900s Emergent era: 21st century
What was the signal event of the transition from the era of infectious disease epidemiology to the era of chronic disease epidemiology?
Evidence that smoking caused lung cancer
Which type of study design is usually considered the most scientifically rigorous?
Experimental
Selection bias occurs in a case-control study if cases and controls are selected differently based on their:
Exposure status
Before a causal relationship between exposure and outcome can be considered, the internal validity of the study must be established.
False
Cohort studies must be conducted within 5 years.
False
Confounding needs to be eliminated, while effect measure modification is a natural phenomenon that should be retained
False
Cross-sectional studies evaluate associations using the population rather than the individual as the unit of study.
False
Differential misclassification always leads to bias toward the null.
False
Epidemiologists agree on the specific steps in the method of causal inference.
False
Epidemiologists can tell if confounding is present by examining the strength of the crude measure of association.
False
Generalization of study results to other populations is more important than establishing the internal validity of a study.
False
Hill's causal criteria should be used systematically as rigid criteria for establishing causal inference.
False
If effect measure modification is present, then the stratified measures of association should be standardized or pooled.
False
It is always impossible to infer temporality from a cross-sectional study.
False
It is okay to compare the results of several studies even when the case definition is different across the studies.
False
It is possible to calculate the attributable proportion and the population attributable proportion using an odds ratio (OR).
False
John Snow's theories about the transmission of cholera were disputed for several years after conducting his famous study in London.
False
Selection bias occurs in a cohort study if loss to follow-up is related to exposure.
False
Sources of data for outcomes in a cohort study are much different than sources of data for exposures.
False
The United States ranks first in the world in life expectancy for both males and females.
False
The best way to evaluate effect measure modification is to compare the crude measure of association and the adjusted measure of association.
False
The criteria for case definitions are different in case-control studies than in other types of epidemiologic studies
False
The direct method of standardization is used when the numbers of deaths in each age group in the study population are too small to calculated stable age-specific rates.
False
The latent period is the same as the induction period.
False
The population risk difference is derived by subtracting risk in the unexposed group from risk in the exposed group.
False
The term "epidemic" refers only to an infectious disease outbreak.
False
The two primary measures of disease occurrence calculated from cohort studies are prevalence and cumulative incidence.
False
Prevalence is most useful for determining the rate and cause of disease.
False - Prevalence is most useful for understanding the burden of disease in a population and for allocating resources. Incidence rate is most useful for determining the rate of disease, and either incidence measure is useful for determining cause of disease.
The components of epidemiology include
Frequency and distribution, population, disease determinants, and control
Which control group is often used in occupational cohort studies when internal controls are not available?
General population
Which control group may suffer from the "healthy worker effect" in a cohort study?
General population
People who volunteer for clinical trials tend to be different from people who do not volunteer. What effect would this have on a study?
Generalizability of results
What was Robert Koch's theory of causation based on?
Germ theory
If you wanted to read about the life expectancy of males and females in the U.S. population, which would be a likely source of this information?
Health, United States
An important work that helped mark the transition from the Social Reform Era to the Infectious Disease Era was the:
Hele-Koch Postulates
Effect measure modification is also known as:
Heterogeneity of effect
What is the most appropriate measure of new-onset disease frequency in an open population?
Incidence Rate
The number of live-born babies who die of sudden infant death syndrome during the first year of life per 100,000 baby-years of follow-up. This measure of disease frequency is:
Incidence rate
Which measure of incidence has person-time in the denominator?
Incidence rate
If the diagnostic criteria of a disease were to change and become stricter than the previous criteria, what would you likely see in the data on this disease?
Incidence would decrease
What is the interval of time between the action of a cause and disease onset?
Induction period
The classic analysis for an experimental study is:
Intent to treat
Why are "odds" calculated in a case-control study?
It is the only measure that can be calculated.
In the United States, a graph of the relationship between age and mortality rate is:
J shaped
One of the earliest experimental studies on scurvy was conducted by:
James Lind
Who conducted a thorough analysis of the water drinking habits to investigate the source of a cholera epidemic in London?
John Snow
If the exposure prevents the disease, then the relative measure would be:
Less than 1.0
Interviewer bias:
May occur in all study designs
Which mortality rate is considered a sensitive indicator of the overall health of a population?
Mortality rates of infants
Which of the following is the principal source of data on the health of the civilian, non-institutionalized population of the United States?
National Health Interview Study
If the True RR is 2.0 and the Adjusted RR is 3.0, confounding is said to be:
Negative
A population in which members come and go is considered a(n) ________ population.
Open and dynamic
Primary prevention efforts are targeted at the ___________.
Pathological onset stage
Which of the following measures would tend to be larger in the same population?
Period prevalence
New drug trial phase that is conducted to show that the experimental therapy has an advantage over a standard therapy.
Phase 3
The existence of a biological mechanism for a disease caused by a specific exposure is an example of which of Hill's criteria?
Plausibility
In the natural history of disease, the period from the pathological onset of disease to the first appearance of signs and symptoms is referred to as the __________.
Preclinical phase
The main way to measure the feasibility of a screening program is with ________.
Predictive value
The percentage of senior boys who are fathers at the time of graduation. This measure of disease frequency is:
Prevalence proportion
The probability that a study result is due to chance is called
Random error
Experimental studies are less likely than cohort studies to suffer from confounding by severity due to:
Randomization
One way to sample controls from a prospective cohort, to form a nested case-control study, is to sample controls throughout the period of follow-up, each time a case is identified. This type of sampling is called:
Risk set sampling
When differential surveillance, diagnosis or referral is related to the exposure in a case-control study, the resulting bias is likely to be:
Self-selection bias
Hill's causal criteria were well known for supporting a causal relationship between which two things?
Smoking and lung cancer
One exposure causing one effect is an example of which of Hill's criteria?
Specificity
A "complete causal mechanism" that inevitably produces disease is known as a what?
Sufficient cause
One way to sample controls from a prospective cohort, to form a nested case-control study, is to select non-cases at the end of the study. This type of sampling is called:
Survivor sampling
In effect measure modification, when one factor enhances the effect of another, the relationship is said to be:
Synergistic
The best statistical test for effect measure modification is:
The chi-square test for homogeneity.
What are the main results of non-compliance in an experimental study?
The final sample size is smaller than anticipated ; statistical power of the study is reduced ; a smaller difference between the treatment and control groups is observed
To calculate the attributable portion (AP) among the exposed, you would use what?
The risk in the exposed and unexposed
A "sufficient cause" could also be described as one pathway for getting a specific disease.
True
A causal relationship between exposure and outcome must be asymmetrical.
True
A major difference between preventive and therapeutic trials is that the participants are healthy in one and diseased in the other.
True
A relative measure of comparison is based on the ratio of two frequency measures.
True
A tenet of the sufficient-component causal model is the idea that disease can originate from several different sufficient causes.
True
Age is an important personal factor in disease because it reflects both the aging process and previous experiences to harmful exposures.
True
An absolute measure of comparison is based on the subtraction of two frequency measures.
True
An age-adjusted death rate is a hypothetical index.
True
An important difference between an observational study and an experimental study is that exposures are assigned to participants in experiments.
True
Attack rate is a type of cumulative incidence.
True
Case fatality rate is a type of cumulative incidence.
True
Cohort studies are also called "follow-up," "incidence," and "longitudinal" studies.
True
Cohort studies are best used when investigators want to learn about multiple effects of an exposure.
True
Confounding may be accounted for in either the design of the study or analysis of the data.
True
Cumulative incidence can be obtained from an incidence rate.
True
Data from death certificates should be evaluated carefully because inconsistencies may occur when the International Classification of Disease (ICD) codes are changed.
True
If stratum-specific estimates of a relationship between exposure and outcome are different, we can conclude that the variable on which we are stratifying is an effect measure modifier.
True
In a case-crossover study, one person serves as both case and control.
True
In addition to studying causes of disease, case-control studies can be used for problem-solving activities within public health practice.
True
In confounding, we are interested in whether the measure of association is distorted by a third variable, whereas in effect measure modification, we are interested in whether the measure of association differs across levels of a third variable.
True
In the sufficient-component causal model, blocking one component in a "causal pie" could prevent the disease from occurring through that pathway.
True
It is not enough to determine the presence of confounding; an investigator must also determine the magnitude and direction of confounding.
True
It is possible to calculate the attributable proportion and the population attributable proportion using an odds ratio (OR).
True
Lead time can vary from person to person
True
Length-bias sampling occurs because screening tends to identify people with the less aggressive forms of disease.
True
Misclassification of exposure or disease may be either differential or non-differential.
True
Modern epidemiology views the case-control study as a method of sampling a population.
True
Most epidemiologists consider Hill's criterion of "specificity" useless.
True
Non-differential misclassification of dichotomous variables biases results toward the null.
True
One indication that effect measure modification is present is that the size of a measure of association changes according to the level of a third variable.
True
Pancreatic disease is suitable for screening because it is a serious condition.
True
Primary prevention efforts include activities that prevent onset of disease.
True
Providing study participants with placebos or sham treatments permit participants, investigators, and healthcare providers to be masked.
True
RD is the excess risk or rate associated with the exposure.
True
Recall bias is a form of information bias that occurs when there is a differential level of accuracy in information provided by compared groups.
True
Self-administered questionnaires may improve the accuracy of questionnaire data.
True
Sensitivity and specificity of a screening test speak to the validity of the test.
True
Spot maps are helpful in showing the geographic distribution of cases but should not be used to assess the risk of disease.
True
Standardizing to a younger population results in a lower age-adjusted death rate.
True
Study participants are masked in single-masked, double-masked, and triple-masked studies.
True
Tertiary prevention efforts include activities that target people with existing disease.
True
The "counterfactual ideal" states that the best comparison group in a cohort study would be the same individuals in the exposed group, had they not been exposed.
True
The National Health Care Surveys are a group of surveys that provide information on the use and quality of health care in a number of different settings.
True
The counterfactual ideal is used to guide the selection of a comparison group in order to minimize confounding.
True
The crude death rate is a good measure of the overall magnitude of mortality in a population.
True
The impact of an exposure on a population is a function of the rate or risk difference (RD) and the proportion of exposed individuals in a population.
True
The induction period is the time between the causal action of exposure and the onset of disease.
True
The most appropriate measure for a closed cohort is cumulative incidence.
True
The most commonly used causal criteria proposed by Sir Austin Hill are consistency, strength of association, biological plausibility, and biological gradient.
True
The odds ratio can be conceptualized as either a disease odds ratio or an exposure odds ratio.
True
The prevalence of a disease is related to the incidence rate and duration of the disease.
True
The rationale behind using dead controls in a case-control study is for comparability of data collection procedures between cases and controls.
True
There are both causal and non-causal associations, and causal inference is a method for distinguishing between the two.
True
To calculate the population attributable proportion from a case-control study, only the odds ratio and the prevalence of exposure in controls are needed.
True
When comparing death rates in the same population for different years, it is essential to adjust the rates to the same standard population before making a comparison.
True
When effect measure modification is present on a relative scale, it is absent on an absolute scale.
True
When researchers evaluate whether study results are true, they are really evaluating the internal validity of the study.
True
Which of these is an example of an active "cause"?
Vitamins
Of the early key figures in the history of epidemiology and demography, which one is credited for developing the British system for vital statistics?
William Farr
Which of the following would be a special cohort?
Workplace site Cancer patients
The criteria of a confounder includes:
an association with the exposure in the population that produces the cases An independent risk factor for the outcome of interest That it cannot be an intermediate step in the pathway between the exposure and disease
The "Healthy Worker Effect" occurs because a relatively healthy worker population is being compared with a less healthy general population, which includes both healthy and sick people. When comparing these populations on risk of disease from a specific exposure, the estimate will tend to be:
an under-estimate of the association between exposure and disease comparing workers with the general population.
Ways to minimize recall bias in a case-control study include:
assuring complete and accurate exposure ascertainment through structured questionnaires Selecting a diseased control group Relying on biological measures and pre-existing records for exposure information
Confounding can be described as:
both the mixing of the effects of exposure, outcome, and a third variable, and the failure of the comparison group to reflect the counterfactual experience of the exposed group.
Recall bias in a case-control study is introduced when:
cases recall exposure differently from controls
The best way to avoid selection bias from loss to follow-up in a cohort study is to:
change participants' exposure status to form equal groups
The main purpose of adjusting death rates for age is to:
compare mortality across different populations. control for differences in the age distributions of populations. eliminate the effects of age when comparing populations.
The measures of association most often estimated from a cohort study are:
cumulative incidence ratio and incidence rate ratio
Homogeneity of effect means:
effect measure modification is absent Stratum specific measures of association between an exposure and outcome are nearly the same for each stratum of a third variable
Some uses of a case-control study include which of the following activities?
evaluating the effectiveness of vaccines Evaluating preventative measures Investigating disease outbreaks
Major advantages of a case-cross-over study are which of the following?
fewer subjects are needed Cases and controls have similar characteristics It is easier to get controls
Ways to minimize interviewer bias include:
masking the interviewer to exposure or case status Using closed-ended, easy to understand questions training interviewers
Ways to control confounding in the design of the study include:
matching, randomization, restriction
One way to reduce the possibility of self-selection bias in a case-control study is to:
obtain high participation rates among cases and controls
What is an example of a passive "cause"?
sex
Characteristics of a cause include what?
statistical dependence between causal factor and outcome, time order, direction
An association is considered valid if which the following explanations has been eliminated?
systematic bias, confounding, random error
The crude death rate can be expressed as:
the number of deaths divided by the population-at-risk. a weighted sum of the age-specific death rates and the proportions of the population by age.
Retrospective cohort studies should be used when:
the outcome of interest has a long induction and latent period
One disadvantage of using existing records for information on exposures in a cohort study is that:
the records were collected for other purposes and may not have all the information needed for the study question
John Snow's epidemiologic study of the cause of the London cholera epidemic could be considered a "natural experiment."
true
The denominator of prevalence includes people who are sick, healthy, at risk, and not at risk.
true