How to Read County Health Rankings: A Michigan Guide

Every year, the Robert Wood Johnson Foundation and the University of Wisconsin Population Health Institute release County Health Rankings for all counties in the United States, including all 83 Michigan counties. These rankings are widely cited in community planning, grant applications, and public health work. Here is what they actually measure and how to use them.

Two Separate Rankings, Not One

The most important thing to understand: County Health Rankings produce two distinct rankings for each county, not one.

• Health Outcomes: How long people live and how healthy they feel. This includes premature death (years of potential life lost) and self-reported health status, physical unhealthy days, and mental unhealthy days.
• Health Factors: Conditions that influence health, including health behaviors (smoking, obesity, physical inactivity, alcohol use), clinical care access, social and economic factors (education, employment, income, family stability), and physical environment (air quality, housing).

A county can rank well on outcomes but poorly on factors, meaning residents are currently healthy but live in conditions that predict worse health ahead. Or vice versa.

What the Rankings Don't Tell You

Rankings are relative, not absolute. A county ranked 40th out of 83 in Michigan might be doing reasonably well on any absolute measure. That ranking simply means 39 counties had better numbers that year. Year-over-year rank changes can reflect changes in your county, changes in other counties, or statistical noise in the underlying data.

County-level data is also averaged across geographies that can contain significant internal variation. Wayne County, which includes Detroit, will have very different health conditions across its communities that a single county rank can't capture.

Key Health Indicators in Michigan Signals

Michigan Signals pulls several health metrics used in County Health Rankings or from similar sources:

• Adult obesity rate: Percentage of adults with BMI ≥ 30, from CDC PLACES (small area estimates derived from BRFSS survey data)
• Adult smoking rate: Current smokers, from CDC PLACES
• Diabetes prevalence: Diagnosed diabetes among adults, from CDC PLACES
• Mental health days: Average mentally unhealthy days per month, from CDC PLACES
• Uninsured rate: Share of adults without health insurance, from CDC PLACES
• Physical inactivity rate: Adults reporting no leisure-time physical activity, from CDC PLACES

How to Use This Data

Health data is most useful when used comparatively and over time. A single county's obesity rate means more when you know how it compares to neighboring counties, the state average, and national benchmarks. Michigan Signals is building toward comparative views across Michigan counties as more dashboards come online. You can already compare health data across counties like Oakland, Wayne, and Washtenaw.

For community organizations and local governments, these metrics are useful for identifying where to focus resources, tracking whether interventions are working over time, and making the case for funding and policy changes.

Data Sources

• CDC PLACES: County and local-level health estimates using the CDC's Behavioral Risk Factor Surveillance System (BRFSS), combined with Census and other data via multilevel regression and poststratification. See CDC PLACES.
• County Health Rankings: Robert Wood Johnson Foundation / University of Wisconsin Population Health Institute. Published annually.