Similarly, policies related to ad-hoc export restrictions and food aid, state-trading and the effects of changes in price volatility are not explicitly modelled. As such, the impacts, and possible gains from the reform, of these policies are not part of the analysis conducted in this study. Therefore, for a number of these measures, reforms would be expected to yield additional impacts to those presented in this study (see, for example, Winchester, 2009). These groups include a wide range of policy measures employed by governments. Non-tariff barriers generally refer to barriers that exist for products and services moving across borders unrelated to taxes and quotas. They include measures such as Sanitary and Phyto-Sanitary (SPS) and Technical Barriers to Trade (TBT).