Epidemiology & Biostatistics: 2026 Exam
Practice
Study Designs, Statistical Methods & Public Health Metrics (100 Questions)
1. What is the fundamental definition of "Relative Risk" (RR)?
A) The absolute difference in incidence between two groups.
B) The ratio of the probability of an outcome in the exposed group to the probability of an
outcome in the control group.
C) The average number of cases per year.
D) The standard deviation of the mean.
Correct Answer: B) The ratio of the probability of an outcome in the exposed group to the
probability of an outcome in the control group.
2. Which study design is considered the "gold standard" for determining causality in
clinical research?
A) Case-control study
B) Randomized Controlled Trial (RCT)
C) Cross-sectional study
D) Case series
Correct Answer: B) Randomized Controlled Trial (RCT)
3. What does "Odds Ratio" (OR) measure?
A) The difference in prevalence between groups.
B) The ratio of the odds of an event occurring in one group to the odds of it occurring in another.
C) The probability of a Type I error.
D) The correlation coefficient.
Correct Answer: B) The ratio of the odds of an event occurring in one group to the odds
of it occurring in another.
4. A p-value of < 0.05 indicates:
A) A 5% probability that the observed results occurred by random chance.
B) A 95% certainty that the null hypothesis is true.
C) The effect size is large.
D) The study has no bias.
Correct Answer: A) A 5% probability that the observed results occurred by random
chance.
,5. What is the definition of "Incidence"?
A) The total number of people currently living with a disease.
B) The number of new cases of a disease in a specific population over a defined time period.
C) The number of deaths caused by a disease.
D) The average duration of a chronic condition.
Correct Answer: B) The number of new cases of a disease in a specific population over a
defined time period.
6. "Prevalence" is defined as:
A) The number of new cases diagnosed in a year.
B) The total proportion of a population that has a disease at a specific point in time.
C) The mortality rate of a condition.
D) The rate of disease transmission between individuals.
Correct Answer: B) The total proportion of a population that has a disease at a specific
point in time.
7. How do case-control studies differ from cohort studies?
A) Case-control studies start with the outcome and look backward; cohort studies start with the
exposure and look forward.
B) Cohort studies involve laboratory animals; case-control studies involve humans.
C) Case-control studies are always more expensive.
D) There is no difference in methodology.
Correct Answer: A) Case-control studies start with the outcome and look backward;
cohort studies start with the exposure and look forward.
8. "Selection Bias" occurs when:
A) The sample size is too large.
B) The participants in the study are not representative of the target population, leading to
skewed results.
C) The statistical software calculates the wrong mean.
D) All participants are chosen randomly.
Correct Answer: B) The participants in the study are not representative of the target
population, leading to skewed results.
9. What is a "Confounding Variable"?
A) A variable that the researcher ignores.
B) An outside influence that changes the effect of a dependent and independent variable,
leading to a false association.
C) The independent variable.
D) The primary outcome measure.
, Correct Answer: B) An outside influence that changes the effect of a dependent and
independent variable, leading to a false association.
10. "Sensitivity" of a diagnostic test is:
A) The ability to correctly identify those who have the disease (True Positive Rate).
B) The ability to correctly identify those who do not have the disease (True Negative Rate).
C) The cost of the test kit.
D) The time it takes to get results.
Correct Answer: A) The ability to correctly identify those who have the disease (True
Positive Rate).
11. "Specificity" of a diagnostic test is:
A) The rate of false negatives.
B) The ability to correctly identify those who do not have the disease (True Negative Rate).
C) How fast the test produces an answer.
D) The total accuracy of the test.
Correct Answer: B) The ability to correctly identify those who do not have the disease
(True Negative Rate).
12. A 95% "Confidence Interval" (CI) means:
A) There is a 95% chance that the interval contains the true population parameter.
B) 95% of the data points fall within the interval.
C) The test is 95% accurate.
D) The study needs to be repeated 95 times.
Correct Answer: A) There is a 95% chance that the interval contains the true population
parameter.
13. A "Type II Error" (False Negative) occurs when:
A) You reject the null hypothesis when it is actually true.
B) You fail to reject the null hypothesis when it is actually false.
C) You calculate the mean incorrectly.
D) You have a small sample size.
Correct Answer: B) You fail to reject the null hypothesis when it is actually false.
14. What is a "Meta-Analysis"?
A) A review of a single patient's records.
B) A quantitative statistical synthesis of results from multiple independent studies on the same
topic.
C) A qualitative interview with a scientist.
Practice
Study Designs, Statistical Methods & Public Health Metrics (100 Questions)
1. What is the fundamental definition of "Relative Risk" (RR)?
A) The absolute difference in incidence between two groups.
B) The ratio of the probability of an outcome in the exposed group to the probability of an
outcome in the control group.
C) The average number of cases per year.
D) The standard deviation of the mean.
Correct Answer: B) The ratio of the probability of an outcome in the exposed group to the
probability of an outcome in the control group.
2. Which study design is considered the "gold standard" for determining causality in
clinical research?
A) Case-control study
B) Randomized Controlled Trial (RCT)
C) Cross-sectional study
D) Case series
Correct Answer: B) Randomized Controlled Trial (RCT)
3. What does "Odds Ratio" (OR) measure?
A) The difference in prevalence between groups.
B) The ratio of the odds of an event occurring in one group to the odds of it occurring in another.
C) The probability of a Type I error.
D) The correlation coefficient.
Correct Answer: B) The ratio of the odds of an event occurring in one group to the odds
of it occurring in another.
4. A p-value of < 0.05 indicates:
A) A 5% probability that the observed results occurred by random chance.
B) A 95% certainty that the null hypothesis is true.
C) The effect size is large.
D) The study has no bias.
Correct Answer: A) A 5% probability that the observed results occurred by random
chance.
,5. What is the definition of "Incidence"?
A) The total number of people currently living with a disease.
B) The number of new cases of a disease in a specific population over a defined time period.
C) The number of deaths caused by a disease.
D) The average duration of a chronic condition.
Correct Answer: B) The number of new cases of a disease in a specific population over a
defined time period.
6. "Prevalence" is defined as:
A) The number of new cases diagnosed in a year.
B) The total proportion of a population that has a disease at a specific point in time.
C) The mortality rate of a condition.
D) The rate of disease transmission between individuals.
Correct Answer: B) The total proportion of a population that has a disease at a specific
point in time.
7. How do case-control studies differ from cohort studies?
A) Case-control studies start with the outcome and look backward; cohort studies start with the
exposure and look forward.
B) Cohort studies involve laboratory animals; case-control studies involve humans.
C) Case-control studies are always more expensive.
D) There is no difference in methodology.
Correct Answer: A) Case-control studies start with the outcome and look backward;
cohort studies start with the exposure and look forward.
8. "Selection Bias" occurs when:
A) The sample size is too large.
B) The participants in the study are not representative of the target population, leading to
skewed results.
C) The statistical software calculates the wrong mean.
D) All participants are chosen randomly.
Correct Answer: B) The participants in the study are not representative of the target
population, leading to skewed results.
9. What is a "Confounding Variable"?
A) A variable that the researcher ignores.
B) An outside influence that changes the effect of a dependent and independent variable,
leading to a false association.
C) The independent variable.
D) The primary outcome measure.
, Correct Answer: B) An outside influence that changes the effect of a dependent and
independent variable, leading to a false association.
10. "Sensitivity" of a diagnostic test is:
A) The ability to correctly identify those who have the disease (True Positive Rate).
B) The ability to correctly identify those who do not have the disease (True Negative Rate).
C) The cost of the test kit.
D) The time it takes to get results.
Correct Answer: A) The ability to correctly identify those who have the disease (True
Positive Rate).
11. "Specificity" of a diagnostic test is:
A) The rate of false negatives.
B) The ability to correctly identify those who do not have the disease (True Negative Rate).
C) How fast the test produces an answer.
D) The total accuracy of the test.
Correct Answer: B) The ability to correctly identify those who do not have the disease
(True Negative Rate).
12. A 95% "Confidence Interval" (CI) means:
A) There is a 95% chance that the interval contains the true population parameter.
B) 95% of the data points fall within the interval.
C) The test is 95% accurate.
D) The study needs to be repeated 95 times.
Correct Answer: A) There is a 95% chance that the interval contains the true population
parameter.
13. A "Type II Error" (False Negative) occurs when:
A) You reject the null hypothesis when it is actually true.
B) You fail to reject the null hypothesis when it is actually false.
C) You calculate the mean incorrectly.
D) You have a small sample size.
Correct Answer: B) You fail to reject the null hypothesis when it is actually false.
14. What is a "Meta-Analysis"?
A) A review of a single patient's records.
B) A quantitative statistical synthesis of results from multiple independent studies on the same
topic.
C) A qualitative interview with a scientist.
