identifying price bubbles in chicken and beef meat markets with rational expectations

introduction: continuous fluctuations in the prices of agricultural commodities have a significant effect on the situation of countries, especially developing countries in the world. in the short term, the impact of price shocks on imports of agricultural commodities and balance of payments and foreign exchange reserves is considerable in developing countries and it has negative effects on social security programs in these countries. in the long- run, these fluctuation effects on specialization of resources in production and development in agricultural sector delays. if price volatility to rise out of the market principals, increases in commodity prices in special times and for special products translates to bubble pick. friedman’s theory on efficient markets underlines that, given rational behavior and rational expectations, the price of an asset will always reflect market fundamentals. therefore, the main question is whether the forces of demand and supply, or explosive behavior (bubbles) generate price volatility mutations. if price volatility is due to market demand and supply conditions, a series of policies, including reducing demand or increase in supply can be effective to reduce volatility. however, if price fluctuations are for reasons beyond market factors, changes in supply or demand fluctuations may be more severe and worsen the situation of the producer and the consumer. hence, it is important, especially for policy makers to determine that whether the market factors or factors outside of market cause fluctuations in the market. material and methods: in the present study, by applying the generalized version of the sup augmented dickey-fuller (gsadf) test, bubble behavior identified. for this test, time series data from 2002 to 2013 that collected on a monthly basis, was used. study variables include the chicken and beef prices. since in the internal investigations, discussing for speculative bubbles in commodities in agricultural products not addressed, it is important to address this issue. these products, select from this perspective that these goods regularly have price volatility over the past years (mainly increase) and therefore, faced with mass and low production. as a result, consumers sometimes have not access to a sufficient quantity of these goods or the supply too much in some periods and vice versa. results and discussion: our findings suggest that food commodities exhibited bubble behavior during mentioned years. these mutations of explosive behavior are, in general, short-lived. assessing trends in the price of chicken show those four cycles of bubble behavior have seen for this product. in the meat market, there are important reasons and factors behind these fluctuations. fluctuations in the price of inputs, especially after subside targeting in iran in 2010, increasing the general level of prices and inflation, consumer cross-sectional volatility (changes in demand) and low ability to store the meat for a long time, not full replacement of fresh poultry meat to freeze and finally and the most important factor the elimination of subsidies for agricultural inputs in recent years are the important factors that affect price and production volatility in recent years in iran meat industry. for the price of beef, just two short-term and long-term bubbles appear in the studied period. rising meat prices due to the rising cost of inputs such as animal fodder and a variety of animal feed, animal drugs, high cost of packaging, transportation problems, related to subsidize livestock inputs, labor and the total inflation are the most important factors for price fluctuations in beef meat.it should be noted that price fluctuations in the price of chicken meat are more and more severe than the price of red meat. the reason for more fluctuations in the price of chicken meat is that per capita consumption of chicken meat is larger than red meat and the level of price for this meat is lower than red meat. therefore, customers can buy it even when the price of chicken meat increases from its mean. the price of red meat is about 4 to 5 times of chicken meat and therefore volatility in the price of red meat can considerably affect on real income and consumption by consumers. conclusion: considering the results and given the importance and influence of external factors on the price volatility of food commodities, we propose the strategies for reducing price volatility mutations and thus reduce the bubble behavior, such that it can be mentioned to apply the appropriate policy of import and export to control the market fluctuations and prices. it is recommended that the daily and monthly prices of major agricultural products such as meat, scrutinized and assessed carefully in order to determine the real parts of price fluctuations for better policy considerations.