The main question in any assessment of the labour market effects of trade is how trade affects a country′s overall employment rate and average wages. In particular, are there net labour market gains from increased trade openness when all sectors are considered? It is important to clarify here that even if there were net labour market losses from trade, thus would not imply that the net overall effect of trade is negative, because the effect on wages and employment is only one way in which trade affects an economy′s welfare. Trade also affects welfare through its effect on other markets. For instance, trade reduces prices in product markets, thus increasing real wages and lowering the prices of inputs. Amiti et al.（2017） show that imports from China have decreased the manufacturing price index in the United States by almost 8 per cent between 2000 and 2006. According to Handley and Limao（2017） , the additional policy certainty alone that China′s WTO accession has given to US investors is responsible for a price drop equivalent to a 13 per cent tariff decrease.