Abstract Objective To quantify impacts of early Affordable Care Act (ACA) Medicaid expansions on Medicaid participation for primary care physicians. Data Sources The study uses secondary Medicaid Analytic eXtract (MAX) data from the United States for 2009–2012, as well as secondary National Plan and Provider Enumeration System (NPPES) data from the United States for 2015. Study Design The study uses a quasi‐experimental difference‐in‐differences study design where the policy change is Medicaid expansion in six states that adopted early ACA Medicaid expansions during 2010 and 2011: California, Connecticut, the District of Columbia, Minnesota, New Jersey, and Washington. The key outcome variables are five monthly measures of physician participation: the number of Medicaid visits, the number of Medicaid patients, seeing at least 1 Medicaid patient, seeing at least 25 Medicaid patients, and seeing at least 50 Medicaid patients. Data Collection/Extraction Methods The sample consists of all physicians who were active between 2005 and 2015, according to the NPPES. Principal Findings For primary care physicians, Medicaid expansion led to a 29% increase in Medicaid visits (5.88 per month; 95% CI: 2.49–9.27), a 29% increase in Medicaid patients (4.59 per month; 95% CI: 2.16–7.02), and did not affect the probability of any Medicaid participation. Medicaid expansion also led to a 22% increase in the probability of seeing at least 25 Medicaid patients per month (4.58 percentage points; 95% CI: 1.27–7.89) and a 31% increase in the probability of seeing at least 50 Medicaid patients per month (2.99 percentage points; 95% CI: 0.99–4.99). Conclusions Early ACA Medicaid expansions led to increased Medicaid visits for primary care physicians but did not affect the probability of any Medicaid participation. Primary care physicians who had previously served Medicaid patients responded to early ACA Medicaid expansions by serving substantially more Medicaid patients.
I investigate why federal student loans crowd out the private market by exploiting the introduction of graduate PLUS loans, which relaxed the federal borrowing limit on graduate students. After the expansion, students replaced private with PLUS loans nearly one-for-one, but did not increase borrowing. I use credit bureau data to compare private and federal loans, and show that most graduate students could receive private interest rates below the federal rates. Modeling students expected utilities, I find that the insurance provided by the federal income-based repayment option can rationalize most borrowers decisions to take out the higher interest federal loans.
