The results from models of this type depend partly on the assumptions economists have to make for instance about the effect of removing non-tariff trade barriers.

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Detroit ultimately, albeit reluctantly, acquiesced to a U.S.-South Korea trade pact touching on similar issues of non-tariff barriers to trade that Japan raises.

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What happened was, is a group, a subset of APEC countries came together and said let's see if we can create a high-standard agreement that is dealing with tariffs and non-tariff barriers to trade, but let's also incorporate a whole range of new trade issues that are going to be coming up in the future -- innovation, regulatory convergence, how we're thinking about the Internet and intellectual property.

WHITEHOUSE: President Obama at the APEC Business Summit

What's more, efforts to draw up shared procedures and standards for imports lag far behind tariff cuts even though such non-tariff barriers constitute the biggest drag on trade in the region, according to a recent World Bank study.

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Nevertheless, for the past three years, it has made almost no progress in removing myriad non-tariff barriers to intra-group trade.

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But switching from non-tariff barriers to tariffs can go only so far to promote agricultural trade.

ECONOMIST: Agricultural trade

They include getting rid of non-tariff barriers (eg, by harmonising food-safety rules) and allowing free trade in services and government purchases, as well as eliminating the many exceptions to the common tariff.

ECONOMIST: Another blow to Mercosur