This paper provides a guide to understanding physician claims data. Physician claims data reflect the prices and quantity of procedures provided by physicians and billed to insurers. These data are often used by policy analysts, legal professionals, and academics to analyze price dynamics in...

We collect a sample of EU and US in-depth merger investigation, estimate models of the regulatory decisions and use the models to compare merger policies in the two jurisdictions. The approach used allows us to decompose observed differences between merger decisions into regime effects and...

Using a combination of public and internal information, this paper compares and contrasts EU and US merger policies. Common economics seems to lead both authorities to consider remarkably comparable portfolios of mergers once the nominal differences in the regimes (US reviews more cases) are...

Most mergers filed at the enforcement agencies are conglomerate in nature with only minor horizontal overlaps. An enforcement agency may challenge the merger, if any overlap is believed to be adversely affected by the transaction. While the merging firm is entitled to a hearing in federal court,...

Most mergers involve multiple markets. The potential for settlement can vary by the fraction of the overall deal attributable to the markets of concern. (i.e., by the “overlap”). If an antitrust agency challenges a merger having only a small overlap, negotiating a settlement is very likely;...

Difference-in-differences, or “D-in-D,” is perhaps the most broadly applied econometric technique in retrospective analyses of competition matters. We discuss a possible pitfall regarding this procedure. We argue that a positive and significant event variable coefficient is not a sufficient...

Physicians' practices vary widely, as do their effectiveness and reimbursement. Using a merger of six orthopaedic groups in southeastern Pennsylvania, we find that such groups can generate large, anti-competitive price increases without any demonstrated increases in quality (indirectly measured...

As a threshold matter, high market shares are considered informative of potential underlying competitive dynamics, especially issues of market power and dominance. However, as is well known, high shares may not tell the entire story. Beyond issues related to market definition, entry, and...

Issues of spatial competition play a key role in many antitrust matters in terms of both defining relevant markets and evaluating competitive effects. One area where this is particularly important is in retail competition. While detailed data for conducting empirical analyses is available in...

Critical loss analysis is a way to directly implement the hypothetical monopolist test for a product market. The first step of critical loss analysis calculates the “critical loss,” which is the maximum loss in sales that the hypothetical monopolist controlling a candidate market could incur...