Internet advertising has been the fastest growing advertising channel in recent years with paid search ads comprising the bulk of this revenue. We present results from a series of large scale field experiments done at eBay that were designed to measure the causal effectiveness of paid search...

This paper reviews the literature devoted to studying markets for health care services and health insurance. There has been tremendous growth and progress in this field. A tremendous amount of new research has been done in this area over the last 10 years. In addition, there has been increasing...

We introduce a simple and robust approach to answering two key questions in empirical auction analysis: discriminating between models of entry and quantifying the revenue gains from improving auction design. The approach builds on Bulow and Klemperer (1996), connecting their theoretical results...

We analyze the differences between companies owned by private equity (PE) investors and similar public companies. We document that PE-owned companies use much stronger incentives for their top executives and have substantially higher debt levels. However, we find little evidence that PE-owned...

Many firms encourage employees to own company stock through share plans that subsidize the price at favorable rates, but even so many employees do not buy shares. Using a new survey of employees in a multinational with a share ownership plan, we find considerable variation in joining among...

Governments rescue private companies partly to prevent other firms from gaining excessive market power. However, if failing firms exit, new entry may limit remaining firms' market power if there are potential entrants who can be as effective competitors as the firms leaving the market. We...

This paper studies how portfolios with a global investment scope are actually allocated internationally using a unique micro dataset on U.S. equity mutual funds. While mutual funds have great flexibility to invest globally, they invest in a surprisingly limited number of stocks, around 100. The...

Measuring the private returns to R&D requires knowledge of its private depreciation or obsolescence rate, which is inherently variable and responds to competitive pressure. Nevertheless, most of the previous literature has used a constant depreciation rate to construct R&D capital stocks and...