The evolution of the model

County Health Rankings and Roadmaps’ (CHR&R) resources are based on a model that helps us understand what shapes health. In 2025, the University of Wisconsin Population Health Institute introduced a new model of health, which broadens our understanding of the forces shaping community conditions like income, safe housing and well-resourced schools. The new model is an evolution of the 2014 County Health Rankings (CHR) Model of Health, which showed that where we live, learn, work and play influence our health. The new model furthers our understanding by examining who and what influence community conditions.

By revealing and naming how power and societal rules shape community conditions for health, the model guides communities to make informed decisions and take action to improve the root determinants of health and well-being. This, in turn, creates a world where everyone has the chance to thrive. 

Getting to know the UWPHI Model of Health 

Understand some of the key ways that the 2025 UWPHI Model of Health has evolved from the 2014 CHR Model of Health.  

Primary model components: The UWPHI Model of Health has four primary components: Population Health and Well-being, Community Conditions, Societal Rules and Power.

• Population Health and Well-being: In our society, health is often understood to be an individual experience. The new model specifies our focus on population health, the distribution of health within a community and the connectedness of our well-being. Well-being, including both quality of life and the ability of people in communities to contribute to the world, was added to the model to reflect the evidence base of what contributes to population health. Population Health and Well-being expand on the concept of Health Outcomes in the 2014 model.  
• Community Conditions: Safe housing, jobs that pay a living wage and well-resourced schools are among the conditions that make up a healthy community. Our new model describes how society’s rules – both written and unwritten – create community conditions. Community Conditions sharpens the concept of Health Factors from the 2014 model to better reveal how the conditions needed for healthy communities do not occur by chance.  
• Societal Rules: The new model names Societal Rules, or the written and unwritten rules and how they are applied by people who wield power, that shape Community Conditions. Written rules may be formalized and documented in laws, policies, regulations and budgets. Unwritten rules are made up of worldviews, culture and norms. By naming these rules and where power is held, the model helps local leaders and organizers to make positive changes.
• Power: The new model names Power, or the ability to achieve a purpose and to effect change. Power is what is used to create and maintain societal rules. People can build community power when they organize and act together to set agendas, shift public discourse, influence who makes decisions and cultivate relationships with decision makers.

New constructs: The UWPHI Model of Health reflects the latest evidence and theory around what shapes health.  

• Health promotion and harm reduction: The new model introduces health promotion and harm reduction to reflect how the places where we live, learn, work and play encourage or inhibit opportunities for good health. Access to healthy foods, options for physical activity and education around safe sex are examples of opportunities individuals have to make informed choices. Population health measures of health behaviors (e.g., adult smoking and teen pregnancy) continue to be used as proxies to measure community conditions. These constructs were represented as health behaviors in the 2014 model.
• Climate: The new model introduces climate as a condition that shapes population health and well-being. There is emerging evidence that connects climate change to the health of communities through extreme heat, and stronger, longer and more frequent storms and droughts.
• Civic and community resources: The new model introduces civic and community resources as a condition that shapes population health and well-being. Civic and community resources include the physical and social infrastructure that help us stay connected and make community participation possible. Civic and community resources are an evolution of family and social support in the CHR Model.

Summary measures and weights: CHR&R will calculate summary measures for Population Health and Well-being (formerly Health Outcomes) and Community Conditions (formerly Health Factors). There is currently no summary measure for Societal Rules and Power. Summary measures (also referred to as composite indicators or indices) combine individual measures with the intent to capture relevant, multi-part aspects of a concept, such as length and quality of life. To calculate summary measures, component measures are standardized to a single scale (a z-score) and then aggregated using nominal weights assigned according to the model.

The new model introduces a new set of nominal weights. Though the new UWPHI Model of Health does not display the weights like the 2014 model, similar care and attention to theoretical, analytic and pragmatic considerations went into developing the revised weights. The following weights were used to calculate the summary measures with the 2025 model.  

• Population Health and Well-being: Length of Life (50%), Quality of Life (50%)
• Community Conditions: Health Infrastructure (25%), Physical Environment (25%), Social and Economic Factors (50%)

Read more about our methodology for more information on the new weights and how they were derived.