The study looked at how a law called SOX affected auditors. They found that many auditors left the market after SOX. The auditors who left were lower quality. It means they didn't follow rules well and didn't do good audits. The new auditors who took over from them did better work and gave more accurate opinions. This shows that rules and checks helped to raise the quality of audits. So, when lower quality auditors left, clients got better auditing.