Our Methods

The County Health Rankings, a collaboration between the Robert Wood Johnson Foundation and the University of Wisconsin Population Health Institute, measure the health of nearly all counties in the nation and rank them within states. The Rankings are compiled using county-level measures from a variety of national and state data sources. These measures are standardized and combined using scientifically-informed weights. To learn more about research on our methods, see our selected publications.

What We Rank

The County Health Rankings are based on counties and county equivalents (ranked places). Any entity that has its own Federal Information Processing Standard (FIPS) county code is included in the Rankings. We only rank counties and county equivalents within a state. The major goal of the Rankings is to raise awareness about the many factors that influence health and that health varies from place to place, not to produce a list of the healthiest 10 or 20 counties in the nation and only focus on that. 

Learn more about what we rank.

Ranking System

We suggest starting with the County Health Rankings model. It provides the foundation for the entire ranking process.

​Counties in each of the 50 states are ranked according to summaries of a variety of health measures. Those having high ranks, e.g. 1 or 2, are considered to be the “healthiest.” Counties are ranked relative to the health of other counties in the same state. We calculate and rank eight summary composite scores:   

  1. Overall Health Outcomes
  2. Health Outcomes – Length of life
  3. Health Outcomes – Quality of life
  4. Overall Health Factors
  5. Health Factors – Health behaviors
  6. Health Factors – Clinical care
  7. Health Factors – Social and economic factors
  8. Health Factors – Physical environment 

Learn more about the ranking system.

Data Sources and Measures

20 Plus Sources

The County Health Rankings team synthesizes health information from a variety of national data sources to create the Rankings. Most of the data we use are public data available at no charge. Measures based on vital statistics, sexually transmitted infections, and Behavioral Risk Factor Surveillance System (BRFSS) survey data were calculated for us by staff at the National Center for Health Statistics and other units of the Centers for Disease Control and Prevention (CDC). Measures of health care quality were calculated for us by staff at The Dartmouth Institute.

Learn more about our data sources.

Data Quality

The County Health Rankings team draws upon the most reliable and valid measures available to compile the Rankings. Where possible, we provide the margins of error (95% confidence intervals) for our measure values. In many cases, the values of specific measures in different counties are not statistically different from one another; however, when combined using our model, those various measures produce the different rankings.

Learn more about our data quality.

Calculating Scores and Ranks

The County Health Rankings are compiled from many different types of data. To calculate the ranks, we first standardize each of the measures. The ranks are then calculated based on weighted sums of the standardized measures within each state. The county with the lowest score (best health) gets a rank of #1 for that state and the county with the highest score (worst health) is assigned a rank corresponding to the number of places we rank in that state.

Learn more about how we calculate scores and ranks.