The study looked at how rules about how much cash banks must keep on hand affect their behavior. By studying a specific type of cash requirement, the researchers found that when banks have to keep more cash, they lend less money. This can make it harder for people and businesses to get loans. The rules also make it harder for banks to make money, but some of the costs are passed on to customers. However, having these rules in place can help prevent banks from failing during a financial crisis.