(FORTUNE Magazine) – How well are American companies performing in the global marketplace? Don't ask the government. At best, U.S. trade statistics give an outdated and misleading picture of the nation's international position. It was only this year, after all, that the feds began reporting monthly trade figures for services as well as merchandise. The Bureau of Economic Analysis recently studied the trade data for 1991 to see how the trade picture looked under several frameworks. The answer: night, day, and lots in between. America's trade balance -- U.S. exports of goods and services minus imports -- was a negative $28 billion in 1991. But those data missed a vital part of the business U.S. companies do overseas: sales through affiliates, or partly owned companies. These, the BEA noted, are ''an integral part of the nation's economic interaction with the rest of the world.'' Net receipts of U.S. firms from sales by affiliates, the BEA estimates, totaled more than $52 billion in 1991 -- turning the $28 billion trade deficit into a $24 billion surplus. While this alternative approach is arguably a more complete measure of trade's effect on the U.S. economy, the BEA considers it experimental and has no plans to produce it on a continuing basis. All the government trade numbers are based on the location of businesses. But managers interested in competition and market share tend to think in terms of company ownership. So how are American-owned businesses performing internationally? The BEA included data from a National Academy of Sciences research study designed to answer this question. The NAS methodology arrives at a national ''net sales'' figure by adding net cross-border sales to foreigners by U.S.-owned companies; net sales to foreigners by foreign affiliates of U.S. companies; and net U.S. sales to U.S. affiliates of foreign companies. Viewed from this perspective, U.S. companies were doing well indeed, producing a whopping $164 billion surplus in 1991.