MPH Epidemiology & Biostatistics 1 — Questions and Answers
Question 1: What does 'incidence rate' measure in epidemiology?
- The number of new cases in a population over a time period (Correct answer)
- The total number of existing cases at a point in time
- The proportion of deaths among those diagnosed
- The rate of recovery from a disease
Correct answer: The number of new cases in a population over a time period
Incidence rate measures new cases occurring in a defined population during a specified time period.
Question 2: Which study design is considered the gold standard for establishing causality?
- Cross-sectional study
- Case-control study
- Randomized controlled trial (Correct answer)
- Cohort study
Correct answer: Randomized controlled trial
Randomized controlled trials are considered the gold standard because randomization minimizes confounding and allows causal inference.
Question 3: A p-value of 0.03 means:
- There is a 3% chance the null hypothesis is true
- There is a 97% chance the alternative hypothesis is true
- There is a 3% probability of observing results as extreme as these if the null hypothesis is true (Correct answer)
- The study has 97% power
Correct answer: There is a 3% probability of observing results as extreme as these if the null hypothesis is true
A p-value represents the probability of observing results at least as extreme as those found, assuming the null hypothesis is true.
Question 4: What is a confidence interval used for in public health research?
- To determine if a study is ethical
- To estimate the range within which the true population parameter likely falls (Correct answer)
- To calculate sample size requirements
- To adjust for confounding variables
Correct answer: To estimate the range within which the true population parameter likely falls
A confidence interval provides a range of plausible values for the true population parameter based on the sample data.
Question 5: Which measure of disease frequency is most appropriate for chronic diseases with long duration?
- Incidence rate
- Attack rate
- Prevalence (Correct answer)
- Case fatality rate
Correct answer: Prevalence
Prevalence captures all existing cases at a point in time, making it more useful for chronic conditions that persist over time.
Question 6: Relative risk (RR) of 1.0 indicates:
- A strong positive association
- No association between exposure and outcome (Correct answer)
- A strong negative association
- The study was underpowered
Correct answer: No association between exposure and outcome
An RR of 1.0 means the risk in the exposed group equals the risk in the unexposed group, indicating no association.
MPH Epidemiology & Biostatistics 1
What does 'incidence rate' measure in epidemiology?