Fig. 2.

Associations between alternative physician access measures and treatment-specific area treatment rate differentials (ATRDs) at the hospital referral region (HRR) level. Separate plots were drawn for each treatment and access measure combination. Trend lines, drawn with use of the LOESS local regression method, show the bivariate relationship between area treatment rate differential value ranking of HRRs in ascending order (x axis) and the HRR physician access measure (as the percent difference from the mean) (y axis). Mean difference was calculated by subtracting the mean value of the access measure across HRRs from each HRR’s specific access measure value. The values at the upper left corner of each plot represent the Pearson correlation coefficient and p value testing the association between the ATRD and the access measure values across HRRs, weighted by HRR sample size. Data pertaining to per-capita physician supply are represented by “Supply” and are shown in black. Data pertaining to the proportion of all physicians in a given specialty are represented by “Proportion” and are shown in red. PT = physical therapy.