The methodology underlying America`s Health RankingsTM reflects the evolving expectations and role of health in our society and our ability to measure various aspects of health.  This year, the methodology was revised to better capture and reflect the variation in health metrics among the states.  All prior editions have been recalculated to reflect the new methodology such that the 20-year history can be maintained to provide a resource for tracking and evaluating progress.  All years of data are available at www.americashealthrankings.org.  

For each measure, the raw data as obtained from the stated sources and adjusted for age as appropriate is presented and referred to as "value".  All age-adjusted data utilizes the population profile for the middle year of data.  For example, if the data is from 2006 to 2008, the standard population is set at 2007.

The score for each state is based on the following formula.  The score is stated as a decimal.

Often referred to as a "Z-score", this score indicates the number of standard deviations a state is above or below the national mean.  This results in a score of 0.00 for a state with the same value as the national mean.  States that have a higher value than the national average will have a positive score while those with lower values will have a negative score.  Scores are calculated to three decimal places and, to prevent an extreme value from excessively influencing a final score, the maximum score any state could receive for a measure is plus or minus 2.

Confidence intervals, where available, will be presented in future updated to the online version of the tables and calculated according to the description for each metric.  Confidence intervals are presented at a 95% confidence level unless indicated otherwise.

For several measures, such as Infant Mortality and Infectious Disease, the data from multiple years are combined to provide sufficient sample size to be meaningful.  

Where a value for the United States overall is not available, the national average is set at the average value of the states and the District of Columbia.

The overall score was calculated by adding the scores of each measure multiplied by its weight or the percent of total overall ranking.  (Note:  Scores reported for individual measures may not add up to the overall scores due to the rounding of numbers.)

The ranking is the ordering of each state according to value.  Ties in scores are assigned equal rankings.

Overall comparisons to prior years, such as Changes Since 1990, are based upon the relative change in the values of a measure compared to the national average for each measure.  The overall result is the weighted sum of these variations.  The change between years is the summation of all changes between those years for the components included in the models used for the years of interest.

All earlier results have been revised to correct any errors discovered since the release of prior editions. Because of the new methodology, scores in this edition are not comparable to scores presented in prior editions and overall ranks presented in this edition are not comparable to overall ranks in prior printed editions.  However, all prior editions have been recalculated and are available on this site.