How does hospital ownership affect health care providers and health plan performance? The researchers conducted a quantitative meta-analysis of the main findings of the empirical literature on hospital ownership and performance. They examined the significance of ownership effect on performance by statistically combining the information in each independent study (1990-2004), while taking in to account differences in quality of the empirical design. They also noted how studies account for market interaction and selection bias, since ownership conversions do not occur randomly among hospitals, and for-profits do not randomly enter markets. The objective of the study was to provide policymakers evidence-based guidance on a wide range of policies regarding hospital ownership, including setting provider payment and evaluating for-profit conversions in health care markets.