Epidemiology Quiz Study Questions
In what respect does epidemiology differ from clinical medicine?
.-Higher spending for providers. -The population approach contrasts with clinical medicine's concern with the individual. -Epidemiology demonstrates many characteristics of a liberal arts discipline. -Epidemiology is primarily an observational science.
Statistics are an important aspect of evaluating associations What is the difference between a parameter and a statistic? Distinguish between a point estimate and a confidence interval. How does power apply to statistical testing?
.A *parameter* is a measure that describes the entire population, whereas a statistic describes a sample of the population. *Point estimation* gives us a particular value as an estimate of the population parameter. ... Interval estimation gives us a range of values which is likely to contain the population parameter. This interval is called a confidence interval. The *power* or sensitivity of a binary hypothesis test is the probability that the test correctly rejects the null hypothesis (H0) when the alternative hypothesis (H1) is true.
What are some of the risk factors for disease that you experience in your life? Be sure to define what is meant by a risk factor.
.A risk factor is an exposure that is associated with a disease, morbidity, mortality, or adverse health outcome. physical inactivity poor diet diabetes obesity tobacco use
Distinguish between the descriptive and analytical approaches to epidemiology.
.Descriptive epidemiology refers to epidemiologic studies concerned with characterizing the amount and distribution of health and disease within a population. Analytic epidemiology examines causal (etiologic) hypotheses regarding the association between exposures and health conditions. risk and protective factors.
Discuss four uses of epidemiology. For each use give examples that were not mentioned in the book.
.Historical Community health Health services Risk assessment Disease causality
Causality
"To search for causes of health and disease by computing the experience of groups defined by their composition, inheritance and experience, their behaviour and environments."
Define and discuss three of the key characteristics of epidemiology.
*Distribution* -counts (# of people with disease) -mortality rate -population -incidence rate (new cases/total pop) *Patterns (Descriptive)* -person (who) -place (where) -time (when) *Determinants* -risk factors -analytical epidemiology *Population*
Define the following -Epidemiology -Pandemic -Epidemic
*Epidemiology* is concerned with the distribution and determinants of health and diseases, morbidity, injuries, disability, and mortality in populations. Epidemiologic studies are applied to the control of health problems in populations." *Epidemic Level*- The occurrence in a community or region of cases of an illness, specific health-related behavior, or other health-related events clearly in excess of normal expectancy. *Pandemic Level* - An epidemic occurring worldwide, or over a very wide area, crossing international boundaries, and usually affecting a large number of people. Example: the 1918 influenza pandemic (Spanish Flu)
Define the following terms: Association Positive association Negative association Nonlinear association Dose response relationship.
*association* - Refers to a linkage between or among variables; variables that are associated with one another can be positively or negatively related. *positive association* - means that if the value of one variable increases, the value of the other variable increases as well. x ^ y ^ *negative association* - means that if the value of one variable increases, the value of the other variable decreases. x ^ y down *nonlinear association* - correlation where ratio of change is not constant. *dose response relationship* - curve. the plot of a dose-response relationship, which is a type of correlative association between an exposure and an effect.
Name three characteristics of time that are used in descriptive epidemiologic studies and give an example of each one.
*characteristics of time:* clustering seasonal strain
What is the advantage and disadvantage of crude and adjusted rates? What is one of he main purposes of adjusted rates?
*crude rate*: A type of rate that has not been modified to take account of any of the factors such as the demographic make-up of the population that may affect the observed rate. *adjusted rate*: A rate of morbidity or mortality in a population in which statistical procedures have been applied to permit fair comparisons across populations by removing the effect of differences in the composition of various populations. Age is a factor used in rate adjustment.
State three uses for descriptive epidemiologic studies. How could descriptive epidemiologic studies examine the following health issues: -The obesity epidemic in the united states -Abuse of prescription narcotic drugs
*three uses:* -study patterns and prevention of disease -generate hypotheses and interventions -conduct research *obesity:* cohort studies to observe impact on diet types on individuals of different race or age *prescription narcotic drugs:* clinical trials with new alternatives to narcotic drugs.
What are some examples of websites where you might obtain epidemiologic data?
American Public Health Association: http://www.apha.org Society for Epidemiologic Research: http://www.epiresearch.org World Health Organization Statistical Information System (WHOSIS): http://www3.who.int/whosis/menu.cfm
Continuous Variable
Continuous variables are variable that could have an infinite number of values along a continuum. Examples include height, weight, and blood sugar level
Distinguish between period prevalence and incidence. What is the definition of lifetime prevalence?
Incidence and prevalence are interrelated concepts. Factors that cause prevalence to increase: Increase in incidence Longer duration of the case In-migration of cases Prolongation of life of patients without a cure Factors that cause prevalence to decrease: Decrease in incidence Shorter duration of disease In-migration of healthy people Improved cure rate of disease Incidence rate: A rate formed by dividing the number of *NEW* cases that occur during a time period by the number of individuals in the population at risk
What are some examples of racial/ethnic classifications used to describe health characteristics? Name two conditions that that vary according to race/ethnicity.
Lower frequency of asthma reported among Hispanics. Non-Hispanic whites and non-Hispanic blacks less frequently report that they have no usual source of medical care than Hispanics. Incidence of gonorrhea is higher among non-Hispanic blacks than other groups.
Pearson Correlation Coefficient
Measure of association used with continuous variables Varies from -1 to 0 to +1 The value 0 means no association. As r approaches either -1 or +1, the association between two variables becomes stronger. When r is negative, the association is inverse.
Hill's Criteria
Outlines the minimal conditions needed to establish a causal relationship between two items. Temporal Relationship: Exposure always precedes the outcome. If factor "A" is believed to cause a disease, then it is clear that factor "A" must necessarily always precede the occurrence of the disease. This is the only absolutely essential criterion. This criterion negates the validity of all functional explanations used in the social sciences, including the functionalist explanations that dominated British social anthropology for so many years and the ecological functionalism that pervades much American cultural ecology. 2. Strength: This is defined by the size of the association as measured by appropriate statistical tests. The stronger the association, the more likely it is that the relation of "A" to "B" is causal. For example, the more highly correlated hypertension is with a high sodium diet, the stronger is the relation between sodium and hypertension. Similarly, the higher the correlation between patrilocal residence and the practice of male circumcision, the stronger is the relation between the two social practices. 3. Dose-Response Relationship: An increasing amount of exposure increases the risk. If a dose-response relationship is present, it is strong evidence for a causal relationship. However, as with specificity (see below), the absence of a dose-response relationship does not rule out a causal relationship. A threshold may exist above which a relationship may develop. 4. Consistency: The association is consistent when results are replicated in studies in different settings using different methods. That is, if a relationship is causal, we would expect to find it consistently in different studies and among different populations. This is why numerous experiments have to be done before meaningful statements can be made about the causal relationship between two or more factors. 5. Plausibility: The association agrees with currently accepted understanding of pathological processes. In other words, there needs to be some theoretical basis for positing an association between a vector and disease, or one social phenomenon and another. 6. Consideration of Alternate Explanations: In judging whether a reported association is causal, it is necessary to determine the extent to which researchers have taken other possible explanations into account and have effectively ruled out such alternate explanations. 7. Experiment: The condition can be altered (prevented or ameliorated) by an appropriate experimental regimen. 8. Specificity: This is established when a single putative cause produces a specific effect. This is considered by some to be the weakest of all the criteria. The diseases attributed to cigarette smoking, for example, do not meet this criteria. When specificity of an association is found, it provides additional support for a causal relationship. 9. Coherence: The association should be compatible with existing theory and knowledge. In other words, it is necessary to evaluate claims of causality within the context of the current state of knowledge within a given field and in related fields.
How does a prevalence proportion (expressed as number of cases per unit size of population ) differ from an incidence rate?
Prevalence is the number of *existing* cases of a disease or health condition, or deaths in a population at some designated time. Incidence rate is a rate formed by dividing the number of *new* cases that occur during a time period (prevalence) by the number of individuals in the population at risk
Dose Response Curve
The plot of a dose-response relationship, which is a type of correlative association between an exposure and an effect. Threshold refers to the lowest dose at which a particular response occurs. Example: dose-response relationship between the number of cigarettes smoked daily and mortality from lung cancer
Describe the types of information that can be obtained from vital registration system of the US.
Vital events are deaths, births, marriages, divorces, and fetal deaths. The vital registration system in the United States collects information routinely on these events.
