Distribution of propensity scores, defined as the probability of being selected into the NHANES-III cohort, by study (NHANES-III, OAI).

<p>The propensity score (x-axis) is defined as the probability of being selected into the NHANES-III cohort. The percentage of individuals with that propensity score (estimated using Kernel density estimation) in each cohort is shown on the y-axis. The solid line represents NHANES-III, while the dashed line represents OAI.