Are there any studies demonstrating causality? I can think of plenty of reasons diversity would correlate with success. For example, being based in a large city

Are there any studies demonstrating causality? I can think of plenty of reasons diversity would correlate with success. For example, being based in a large city will have a lot of advantages for many businesses, along with having a more diverse hiring pool available that will naturally lead to a more diverse staff. But this doesn't suggest to me that adding a diversity quota or similar policy, all else being equal, will help a company succeed.