Iris Claus: The authors investigate non-tariff measures, or NTMs, which are policy measures, other than ordinary custom tariffs, that may have an economic effect on merchandise trade by changing the price and/or the quantity of goods traded. They include consumption standards and contingent protection but exclude production standards, are widely used by countries around the world, and in many cases their use is valid and justified. For example, governments may impose regulation to ensure certain standards of quality for some products or to protect consumers’ health. Nevertheless, a potential concern with NTMs is that they can be used as protectionist measures, and determining if their purpose is for legitimate or protectionist reasons is difficult.
The economic effects of NTMs may be assessed by their incidence and severity. Incidence can be measured either by a frequency ratio, which is the proportion of product categories covered by one or more NTMs, or...