epidemiology

This week covers foundational epidemiological studies: ecological, cross-sectional, and case-control.

We distinguish studies by:

Subject Selection: How participants are chosen.
Data Collection: Methods for gathering information.
Data Types: Kinds of data collected.
Analysis: Statistical approaches and effect measures (e.g., odds ratio, relative risk).
Design Identification: Unique study structure.
Pros and Cons: Advantages and disadvantages.
Calculations: Practical exercises like odds ratio calculations.

Experimental Studies (Intervention Studies): Involve manipulating subjects (e.g., treatment group vs. control). Less common in human epidemiology due to ethics.
Observational Studies: Gather information and observe natural associations between risk factors and outcomes without manipulation. Ecological, cross-sectional, and case-control studies are all observational.

Prevalence: Existing cases of a condition.
- Point Prevalence: Cases and exposures at a specific time (e.g., cross-sectional studies).
- Period Prevalence: Cases over a defined period.
Incidence: New cases of a disease over a specific time period (e.g., one year).

Number of Observations: Single point in time or extended period.
Directionality of Exposure:
- Past Exposure (Retrospective): Looking back for exposures (e.g., lung cancer and past environmental exposures).
- Future Exposure (Prospective/Longitudinal): Following individuals to observe future disease development after exposure.
Data Collection Methods:
- Primary Data: Investigator collects data directly (e.g., medical exams, interviews).
- Secondary Data: Investigator uses existing data collected by others (e.g., census data).
Timing of Data: When data is collected relative to exposure or disease onset.
Unit of Observation: Who the data is collected on (e.g., individuals, groups).
Availability of Subjects: Factors affecting data acquisition (e.g., age, cognitive status).