Epidemiological Data Analysis

Complete workflow for observational epidemiology — from research question to publication-ready report. Write and run Python code for every step. Never describe what you "would do" — do it.

Step 1: Formulate the Research Question (PECO Framework)

Define Population, Exposure, Comparator, Outcome before touching data.

• Population: Who? (e.g., adults aged 20-79, cancer patients stage III+, ICU admissions)
• Exposure: What factor? (e.g., nutrient intake, drug treatment, gene mutation, environmental pollutant)
• Comparator: Vs. what? (e.g., lowest tertile, unexposed, wild-type, placebo)
• Outcome: What health event? (e.g., disease incidence, survival time, biomarker level, mortality)

Study design check: Does the question require temporality?

• Cross-sectional: prevalence, associations at one time point
• Longitudinal/cohort: incidence, causal inference, temporal relationships
• Case-control: rare outcomes, odds ratios (nested within cohort)
• Clinical trial: intervention effects with randomized controls