Epidemiology and Research Methods Quiz

Epidemiology Fundamentals

• Epidemiology is the study of the distribution and determinants of disease in populations.
• Epidemiological research aims to describe adverse health outcomes (when, where, among whom), explain disease patterns and causes (temporal, sub-populations, disparities), and predict/diagnose those with a disease, prognosticate likelihood of disease, and identify causal factors for disease prevention.

Research Process

• The research process involves observation, theory building, hypothesis formation, empirical testing (data collection and analysis), and inference drawing conclusions.
• This process includes both inductive (from observation to theory) and deductive (from theory to observation) approaches.

Populations & Samples

• Target population is the entire population under investigation.
• Sampling frame is a subset of the target population that is eligible for the study.
• Study sample is the group of participants who are ultimately selected and included in the study.

Types of Sampling

• Probability sampling methods include simple random, stratified, and cluster sampling, which use random selection methods, ensuring each population member has a known probability of inclusion.
• Non-probability sampling does not use random selection. Methods include quota sampling, self-selection, and convenience sampling.

Measures of Occurrence and Contrast

• Measures of occurrence include counts, incidence, and prevalence.
• Measures of contrast compare occurrence rates between groups and include risk/prevalence differences, ratios, odds ratios, incidence rates, survival rates, and time-to-event measures.

Prevalence

• Prevalence is the proportion of a population that has a specific characteristic (disease) at a particular time.
• It is a snapshot of the disease burden in a population.
• Prevalence measures are typically cross-sectional and over a period of time.

Incidence

• Incidence is the rate at which new cases of a disease occur in a defined population over a period of time.
• Incidence measures track new cases among those at risk.

Study Designs

• Randomized Controlled Trials (RCTs): Experimental studies where treatments are randomly assigned to participants.
• Cohort Studies: Observational studies where researchers follow a group of people over time to assess the relationship between exposures and outcomes.
• Case-Control Studies: Observational studies where researchers compare individuals with a disease (cases) to those without (controls) to identify potential exposures associated with the disease.
• Cross-sectional Studies: Observational studies that measure both exposures and outcomes at a single point in time. Cannot establish causation.

Systematic Error (Bias)

• Confounding: A systematic error where a third variable influencing both the exposure and outcome distorts the true association between the exposure and the outcome.
• Selection Bias: A systematic error in the selection of participants or groups that leads to biased results. It includes Berkson's bias, healthy worker effect, self-selection bias, survival bias, and loss-to-follow-up.
• Information Bias: A systematic error in the measurement of exposures, outcomes or confounders. It can lead to over- or underestimation of the association for example recall bias and interviewer bias.