Epi Quizzes and Exams

How many false positives did the test identify?

25

What was the prevalence of the condition in this screening test population?

25%

What is the sensitivity of the screening test?

80%

What is the specificity of the screening test?

83%

You are investigating the role of physical activity in heart disease and suggest that physical activity protects against having a heart attack. While presenting these data to your colleagues, someone asks if you have thought about confounders such as factor X. This factor X could have confounded your interpretation of the data if it meets what criteria? - Is a factor associated with physical activity - Is a factor associated with heart disease - Is a factor not part of the pathway by which physical activity affects heart disease - All of above

All of the above

Which of the following is not a method for controlling the effects of confounding in epidemiologic studies? - Randomization - Stratification - Matching - Blinding - Restriction

Blinding

In which of the following study designs do investigators manipulate the study factor of interest? - Case Control Studies - Cohort Studies - Randomized clinical trials - Community trials - Both C & D - Both B & C

Both C&D

300 depressed persons and 300 persons with no history of depression are administered a questionnaire to assess their prior smoking habits. What type of study is this?

Case-Control

To test the efficacy of a health education program in reducing the risk of foodborne and waterborne diseases, the residents of two Peruvian villages were given an intensive health education program. At the end of two years, the incidence rates of important waterborne and foodborne diseases in these villages were compared with those in two similar villages without any education program.

Community Trial

You would like to assess the extent of health services utilization through your clinic. After selecting a 10% sample of all patient visits during the past six months, you are able to characterize the patient population who used your clinic in terms of age, race, sex, method of referral, diagnostic category, therapy provided, method of payment, daily patient load, and clinic work staff schedules.

Cross-sectional Study

Rates of cholera are determined for each neighborhood in a city and plotted as a function of average neighborhood wealth. What type of study is this?

Ecological

The major purpose of random assignment in a clinical trial is to:

Ensure that study groups have comparable baseline characteristics

Which answer best describes the phenomenon depicted in the figure?

Epidemiologic Transition

The following table describes various strategies, or research approaches, for understanding the sociocultural context of depression. Which of the following describes a qualitative, vs quantitative, approach? c. Ethnographic discourse analysis to identify social meaning of depression b. Standardized interviews via a structured questionnaire with multiple choice response options a. Multivariate regression models to assess correlates of depression d. Both A and B

Ethnographic discourse analysis to identify social meaning of depression

What type of validity is most affected by recruitment and eligibility in a randomized clinical trial?

External Validity (Generalizability)

Two counties in Missouri had equal rates of new Hepatitis A infections for 2005. This is a measure of prevalence.

False

Two counties in Missouri had equal rates of new Hepatitis A infections for 2005. This shows that both counties had the same total number of new cases in 2005.

False

A conceptual framework can be used to:

Help avoid overly simplistic interpretations of the factors that drive racial disparities, re-orient the question from "what is the effect" to "what are the processes responsible for the effect" of race on a health outcome, and recognize sources of structural bias and social factors like racism rather than emphasize only individual-level factors that drive racial disparities

Random error may be reduced by: - Reducing misclassification of exposure status in community-based controls - Increasing the sample size of the study - Minimizing selection bias - All of the above

Increasing the sample size of the study

An advertisement in a medical journal stated that "2,000 subjects with sore throats were treated with our new medicine. Within 4 days, 94% were asymptomatic." The advertisement claims that the medicine was effective. Based on the evidence given above, the claim:

May be incorrect because no control or comparison group was involved

Between 2000 and 2006, the incidence of HIV remained relatively constant, but HIV prevalence steadily increased. You surmise that..

More individuals are surviving with HIV

Case Control Study Measure

Odds Ratio

Cross Sectional Study Measure

Odds Ratio

Suppose the cases in a case-control study gave a more complete response about exposure to potential risk factors than the controls. What responses accurately describe this threat to the validity of study findings? A. Selection Bias B. Recall Bias C. Misclassification Bias D. Systematic error E. Only B, C & D F. All of the above

Only B, C & D

Which measure of screening test validity increases with higher prevalence of the condition?

Positive predictive value

In a town of 55,000, 700 people had pneumonia in 2012. What measure does 700/55,000 represent?

Prevalence

Asthma has a prevalence of 75 per 100,000 population and an incidence of 30 per 100,000 population per year. The introduction of a new treatment controls the disease and prolongs life. What will be the effect of the introduction of this new treatment?

Prevalence will increase

A cohort of 200 smokers and 100 non-smokers are recruited and followed overtime to assess a risk of developing heart disease. What type of study is this?

Prospective Cohort

The entire population of a given community is examined, and all who are judged to be free from bowel cancer are questioned extensively about their diets. These people then are followed for several years to see whether or not their eating habits will predict their risk of developing bowel cancer.

Prospective Cohort Study

You are interested in finding out whether middle-aged men who have premature ventricular contractions are at a greater risk of developing a myocardial infarction than men who's heartbeats are regular. ECG examinations are performed on all male office employees 35 years of age or older who work for oil companies in Houston. The ECG tracings are classified as irregular or regular. Five years later, myocardial infarction rates are compared between those with and without baseline ECG irregularities.

Prospective Cohort Study

To test the efficacy of Vitamin C in preventing colds, army recruits are randomly assigned to one of two groups: one in which 500mg of Vitamin C is administered daily, and one in which 500mg of a placebo is administered daily. Both groups are followed to determine the number and severity of subsequent colds.

Randomized Clinical Trial

Cohort Study Measure

Rate Ratio

The Women's Health Initiative study found the following relative risk (RR) and accompanying 95% confidence interval (CI) for the relationship between hormone treatment and incident breast cancer: RR=1.26, 95% CI: 1.01-1.59. Based on these data, which is the correct inference:

Reject the null hypothesis (where null hypothesis= no difference between treatment groups with respect to breast cancer risk)

RCT Measure

Relative Risk

What is the most appropriate measure of association to calculate from a prospective cohort study? - Incidence rate - Relative Risk - Prevalence - Odds Ratio

Relative Risk

What is the most appropriate measure of association to calculate from a randomized clinical trial? - Relative Risk - Incidence rate - Prevalence - Odds Ratio

Relative Risk

The physical examination records of the incoming freshman class of 1955 at the University of Minnesota are examined in 2015 to see whether their recorded height and weight at the time of admission to the university are related to their chance of developing coronary heart disease by 2010.

Retrospective Cohort Study

In a study to determine the incidence of a chronic disease, 150 people were examined at the end of a three-year period. Twelve cases were found, giving a cumulative risk of 8%. Fifty other members of the initial cohort could not be examined; 20 of these 50 could not be examined because they died. Which source of bias may have affected the study? - Selection bias - Effect Modification - Information bias - Confounding

Selection Bias

In a cohort study that examined the relationship between smoking and risk of bladder cancer, a relative risk of 7.5 was found. This means that:

Smokers had a higher risk of bladder cancer than non-smokers

The strategy which is not aimed at reducing selection bias is: - development of an explicit case definition - standardized protocol for structured interviews - encouragement of high participation rates - enrollment of all cases in a defined time and region

Standardized protocol for structured interviews

According to Hill's criteria, when a study shows that the greater the exposure to a risk factor, the greater the risk of developing the disease, it is said to show a dose-response relationship or that their is a biologic gradient in the relationship.

True

According to Hill's criteria, when a study shows that the greater the exposure to a risk factor, the greater the risk of developing the disease, it is said to show a dose-response relationship or that there is a biologic gradient in the relationship.

True

All rates adjust for the size of the population at risk.

True

Bias is a synonym for systematic error.

True

Temporality tells us if exposure precedes development of disease by a period consistent with a proposed biologic mechanism.

True

The risk difference is considered an absolute measure of effect and is used to quantify the excess burden of disease attributable to a particular risk factor.

True

To be a rate, all individuals in the denominator must be at risk of being in the numerator.

True

True or false? In a retrospective cohort study, incidence rates may be computed for exposure groups.

True

Two counties in Missouri had equal rates of new Hepatitis A infections for 2005. Having the same rate shows that the population's chance of developing Hepatitis A was the same in the two counties in 2005

True

The graph below depicts racial disparities in life expectancy in the US. What type of evidence does this provide?

Type 1 Evidence