APPENDIX EXHIBIT A9.

Physician Group Size by 2014 ACO Participation, 2008–2013, Stratified by Baseline Primary Care Orientation and Baseline Size

SOURCE Authors’ analysis of data from the Centers for Medicare and Medicaid.

NOTES All panels result from separate within-market analyses, presenting the average pre- and post-period value of the dependent variable, by 2012, 2013, or 2014 ACO participation. Physician’s average group size was calculated as the average count of physician billing for outpatient care within a TIN, weighting each TIN by its share of total physicians in the MSA. Primary care orientation was calculated as the share of physicians billing under a TIN with a primary care specialty. ACO is Accountable Care Organization.