Observation Studies Strengths/Weakness

Cross-sectional Strength

Quick, inexpensive, estimates prevalence

Cross-sectional Weakness

Cannot establish causality

Prospective Cohort Strength

Time-aligned exposure-outcome, calculates risk

Prospective Cohort Weakness

Expensive, loss to follow-up

Retrospective Cohort Strength

Less expensive than prospective

Retrospective Cohort Weakness

Potential for missing/incomplete data

Case-Control Strength

Good for rare outcomes

Case-control Weakness

High bias potential, cannot estimate incidence

Nested Case Control Strength

Reduces selection bias

Nested Case Control Weakness

Limited generalizability to external populations

Case Report/Series Strength

Hypothesis-generating

Case Report/Series Weakness

No control group, no causality