Research planning
How to calculate sample size for a health study
Understand confidence level, margin of error, expected proportion, finite populations, and non-response adjustments.
Read the sample size guideLearning hub
Short, practical guides for public health analysis
Use these notes to connect calculator outputs with epidemiological reasoning, study design, and program decisions.
Featured guides
Learn the concept, then use the tool
These applied guides explain common decisions, calculation choices, interpretation errors, and reporting practices.
Disease frequency
Incidence versus prevalence
Learn what each measure answers, how their denominators differ, and when duration changes the relationship between them.
Compare incidence and prevalenceMeasures of association
Relative risk versus odds ratio
Choose the appropriate association measure for cohort, trial, cross-sectional, and case-control studies.
Compare RR and ORMonitoring & Evaluation
How to develop a strong M&E indicator
Turn a program objective into a precise indicator with a defined numerator, denominator, source, frequency, and target.
Build a stronger indicatorFoundation topics
Build confidence across the public health workflow
Epidemiology Basics
Epidemiology studies the distribution and determinants of health-related events in populations. Start by defining the population, time period, case definition, denominator, and purpose of the measure.
Study disease frequencyBiostatistics Basics
Confidence intervals describe precision, while p-values assess compatibility with a null hypothesis. Interpret both alongside effect size, design, bias, and practical importance.
Open confidence interval calculatorResearch Methodology
Cross-sectional studies estimate prevalence, cohorts estimate incidence and risk, case-control studies efficiently examine rare outcomes, and trials evaluate interventions.
Choose a study designPublic Health Concepts
Mortality, case fatality, coverage, incidence, and attack rates answer different operational questions and require carefully defined denominators.
Browse public health toolsMonitoring & Evaluation
Connect inputs, activities, outputs, outcomes, and impact through a theory of change, then monitor a focused set of decision-relevant indicators.
Open M&E tools