Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. There is a growing interest in the measurement of the levels and the costs of agricultural protection. Levels of agricultural protection are measured and compared across countries in various recent studies by national ministries and international organizations [World Bank (1986), FAO (1987a), OECD (1987OECD ( , 1988, USDA (1987, 1988)]. These comparisons may be used, e.g., in inter- It is well-known from this literature that the measurement of agricultural protection has important implications for policy evaluation. Despite this and the fact that nominal and effective rates of protection are widely used in the trade literature, protection levels in agriculture were often measured in a rather crude way. Consequently, policy conclusions were in many cases derived from studies using crude protection levels. Westlake (1987) argues that several studies on agricultural protection ignored transport and marketing costs. His empirical analyses suggest that these costs matter for the magnitude of the measured level of protection, especially in developing countries.
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Documents in EconStor mayByerlee/Sain (1986) show that the measured subsidization of or discrimination against agriculture is strongly affected when overvalued exchange rates are taken into account. Furthermore, they argue that heavily fluctuating world prices distort the measured degree of protection and vote for the use of normal instead of actual world prices in the calculation of protection rates.-2 -Our paper elaborates further how measurement issues are important when agricultural protection is analyzed. It reveals that policy conclusions vary due to the way agricultural protection is measured. We focus on two aspects which have been widely ignored in the literature: price uncertainty and limited substitution. In the first part, we start from the important findings of Byerlee/ Sain (1986). These authors tried to cope with world price uncertainty and derived for the wheat sector the challenging and unexpected result that developing countries do not systematically discriminate against agriculture. We will show that this major finding is heavily dependent on the way price uncertainty is measured. When normal world prices are modelled on the basis of an econometric world wheat model rather than with trend analysis, the qualitative result changes. In the second part, we investigate how the modelling of substitution between agricultural products affects the calculated impacts of given lev...