From question to protocol
Define the research question, primary hypothesis, target population, exposure/intervention, comparator and outcomes before choosing methods. Pre-specify primary and secondary endpoints.
Methodology essentials
Study design
Match design to the question: cross-sectional studies estimate prevalence; case-control studies examine associations efficiently for uncommon outcomes; cohort studies estimate incidence and temporal associations; randomized trials evaluate interventions; diagnostic-accuracy studies compare an index test with an appropriate reference standard.
Sample size and power
Determine sample size prospectively using the primary endpoint, expected effect size, variability/event rate, alpha, desired power and anticipated missingness. Avoid choosing a sample size solely because specimens are available.
Bias and confounding
Identify selection, measurement, information and analytical biases. Predefine confounders and effect modifiers using biological and causal reasoning rather than selecting variables only from univariable P values.
Reproducibility
Use version-controlled protocols, SOPs, calibrated equipment, traceable reagents, blinded/independent review where appropriate, predefined QC thresholds and reproducible analysis code.
Reporting
Use the reporting guideline appropriate to the study design, such as CONSORT, STROBE, PRISMA, STARD, TRIPOD or relevant EQUATOR Network guidance.
Research-use note: This resource is educational and methodological. Study-specific protocols require scientific review, appropriate ethics approval, validated laboratory methods and a prespecified statistical plan.
Planning a research study?
Our research team can help you shape the question, design, sample size and analysis plan for your study.