Using XBRL to conduct a large-scale study of discrepancies between the accounting numbers in compustat and SEC 10-K filings

Compustat is frequently used for both research and decision making. It has been documented that information found in the Compustat database differs from both the information found in other accounting databases and the information disclosed in corporate financial filings (San Miguel 1977; Rosenberg and Houglet 1974; Yang, Vasarhelyi, and Liu 2003; Tallapally, Luehlfing, and Motha 2011, 2012; Boritz and No 2013). In this study, we conduct the first large-scale comparison of Compustat and 10-K data. Specifically, we compare 30 accounting line items of approximately 5,000 companies for the period from October 1, 2011 to September 30, 2012. We find that the values reported in Compustat significantly differ from the values reported in 10-K filings. We also find that the amount and magnitude of the original data alterations introduced by Compustat depend on the type of the accounting item and company characteristics, such as industry and size.