Researchers have struggled to establish a causal relationship between diversity and financial performance—especially at large companies, where decision rights and incentives can be murky, and the effects of any given choice can be tough to pin down. So the authors chose a “lab rat” with fewer barriers to understanding: the venture capital industry. VC firms are fairly flat: Every investor is a decision maker, and choices have clear business consequences. Using publicly available information, researchers can see how similar or different decision makers are and compare decision quality on the basis of investments’ performance.