The County Health Rankings & Roadmaps (CHRR) program draws upon the most reliable and valid measures available, but have in mind that the reliability of measures vary. Where possible, CHRR provided the margin of errors (95% confidence intervals) for measure values. In addition, some variables were age-adjusted. Age-adjustment is a useful strategy to increase the comparability of health measures between counties, but it can also mask the true burden of a health need in a county. Therefore, only some measures are age-adjusted: premature death (YPLL), self-reported health, physically unhealthy days, and mentally unhealthy days and preventable hospital stays.