In line with most auditing research, we classify big-4 accounting firms as high quality assurance providers compared to other assurors types (see Francis, 2004). Accounting firm size is a proxy for quality (auditor independence) because no single client is important to a large auditor and the auditor has a greater reputation to loose (their entire clientele) if they misreport. Due to their size, big-4 firms are also better able to enforce internal mechanisms of control to ensure consistent quality of the assurance reports issued by their members.