US GAAP x normas brasileiras: mensura？？o do impacto das diferen？as de normas no lucro duplamente reportado pelas empresas brasileiras emissoras de ADRS na NYSE

the lack of a single set of accounting rules valid for all countries can lead to conflicting results. for example, among the brazilian issuers of adrs (american depositary receipts) on the nyse (new york stock exchange), cemig presented in 2002 a loss of r$ 12 million according to u.s. gaap (united states generally accepted accounting principles) and, under brazilian regulations, a loss of r$ 1 billion (or 83 times greater). csn also presented in the same year a profit of r$ 6 million under u.s. gaap, compared to a loss of r$ 218 million, according to brazilian standards (ie 30 times higher). this study aims to determine whether differences between brazilian accounting standards and u.s. (u.s. gaap) generate significant impact on the results reported on form 20f by the 30 brazilian issuers of adrs. to measure the effect of these regulatory differences in the results we used the "conservatism index" (ci) of gray, which measures how a national accounting system generates lower ("is conservative") or higher ("is optimistic") profits than u.s. gaap. the mean and median of the ic in the period 2001 to 2005 indicate conservatism of brazilian rules, not confirmed by the student t test, but confirmed by the wilcoxon test at 10% significance. divided in two periods, we obtained an average of 1.2 for ic 2001 to 2002 (significant at 3.3%) and 0.86 for 2003-2005 (significant at 3%), indicating a difference in behavior: brazilian accounting seems more optimistic than u.s. gaap by 2002, becoming more conservative from 2003 until 2005.