Specifically, Big 4 auditors represent high audit quality and non-Big 4 firms represent low audit quality. This is based on the assumption that the Big 4 always provide higher quality audits that communicate the reliability of unobservable financial reports. Of course, this does not mean that non-Big 4 companies intentionally deviate from U.S. GAAP or other relevant reporting standards. However, Teoh and Wong (1993) find that discrepancies between reported figures and actual economic levels are higher for non-Big 4 auditors. DeAngelo (1981) identifies the Big 4 as an appropriate indicator of 'high audit quality, because the brand name and size imply greater reliability through technical expertise. According to Sori et al (2006), Big 4 employees are more qualified and have access to better financial resources, better research facilities and better technologies. This gives them a competitive advantage in conducting large or specialized audits and a greater ability to discover errors or inaccuracies. This argument is supported by the low levels of accounting restatements issued compared to those of non-Big 4 auditors (Eshleman and Guo 2014), and by their extensive specialized training programs (Khurana and Raman).