Lesson 1: Introduction to Epidemiology and Biostatistics

Comprensive practice questions covering the fundamentals of epidemiology, study designs, error management, and statistical regression models based on lecture notes.

What is the definition of epidemiology?

The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control health problems.

Contrast morbidity and mortality as core concepts in epidemiology.

Morbidity refers to illness or disease status, while mortality refers to the death rate.

Identify the three questions addressed by descriptive epidemiology.

Who (person), Where (place), and When (time).

What is the primary direction of a cohort study?

Forward (prospective or retrospective); it moves from Exposure to Outcome.

Which study design is most efficient for studying rare diseases?

Case-control study.

What is the main limitation of a cross-sectional study?

It cannot determine cause and effect or infer temporality because it measures exposure and outcome simultaneously (snapshot).

What are the three components of the Epidemiological Triad?

Host (the organism), Agent (the cause), and Environment (external factors affecting exposure).

How is the Incidence Rate calculated?

$$\text{Number of new cases} \div \text{Population at risk over time}$$

Define point prevalence.

The proportion of people with a disease at a specific point in time, calculated as $\text{Number of existing cases at a point in time} \div \text{Total population at that time}$.

What is the formula for the Case Fatality Rate?

$$\text{Deaths} \div \text{Total diagnosed cases}$$

How is Infant Mortality Rate defined?

$$\text{Deaths in children < 1 year} \div \text{Live births}$$

How does random error differ from systematic error (bias)?

Random error occurs by chance and affects precision, whereas systematic error is a consistent flaw that affects accuracy.

What are two subtypes of information bias?

Recall Bias (cases remember exposures better than controls) and Observer Bias (investigator expectations influence observations).

What is the purpose of randomization in an experimental study?

To eliminate selection bias and balance known and unknown confounders evenly across groups.

Define the levels of blinding: single-blind, double-blind, and triple-blind.

Single-blind: participants are unaware; Double-blind: participants and researchers are unaware; Triple-blind: participants, researchers, and statisticians are unaware.

What three criteria must a variable meet to be a confounder?

1. Associated with the exposure; 2. Independently associated with the outcome; 3. Not an intermediate step in the causal pathway.

When is Logistic Regression typically used in epidemiology?

When the outcome (dependent variable) is binary (has only two categories) and to estimate Odds Ratios ($OR$).

Which regression model is used for time-to-event data?

Cox Proportional Hazards Regression.