نوع مقاله : مقالات پژوهشی
نویسندگان
1 استادیار گروه اقتصاد کشاورزی، دانشکده اقتصاد و توسعه کشاورزی ، دانشگاه تهران، تهران، ایران
2 دانشجوی دکتری اقتصاد کشاورزی
3 استاد گروه اقتصاد کشاورزی
4 دانشیار گروه اقتصاد کشاورزی
چکیده
با توجه به تأثیر همه‌گیری کووید-19 بر تقاضای مواد غذایی در نتیجه اختلال در زنجیره تأمین و تکانه‌های درآمدی، هدف پژوهش حاضر بررسی وجود شکست ساختاری در ترجیحات محصولات دامی (گوشت قرمز، مرغ، تخم مرغ و شیر) مصرف‌کنندگان ایرانی با استفاده از سیستم تقاضای تقریبا ایده‌آل درجه دو و چارچوب رگرسیون سوئیچینگ توسعه یافته توسط اوهتانی و کاتایاما (Ohtani & Katayama, 1986) در بازه زمانی بهار 1394 تا زمستان 1401 بوده است.
جهت محاسبه کشش‌های قیمتی و درآمدی نیاز به داده‌های قیمت و مصرف سرانه محصولات دامی است که در پژوهش حاضر از داده‌های سری زمانی فصلی برای دوره زمانی بهار 1394 تا زمستان 1401 استفاده شده است. اطلاعات مربوط به قیمت محصولات دامی از شرکت سهامی پشتیبانی امور دام گرفته شده است. برای محاسبه مصرف سرانه ابتدا اطلاعات مقدار تولید گوشت قرمز، مرغ، شیر و تخم مرغ از شرکت سهامی پشتیبانی امور دام دریافت شد. سپس با جمع مقدار تولید و مقدار واردات گوشت قرمز، مرغ، شیر و تخم مرغ و کسر کردن مقدار صادرات از جمع مذکور و تقسیم بر جمعیت کشور، مقدار مصرف سرانه محاسبه گردید. مقدار صادرات و واردات گوشت قرمز، مرغ، شیر و تخم‌مرغ از گزارش صادرات و واردات وزارت جهاد کشاورزی که به صورت ماهانه منتشر می‌شود، گرفته شده است.
نتایج بیانگر وجود شکست ساختاری به صورت تدریجی در نتیجه همه‌گیری کووید-19 است. همچنین نتایج نشان می‌دهد که بعد از همه‌گیری کووید-19 کشش خود قیمتی گوشت قرمز و مرغ افزایش چشم‌گیری داشته است. با توجه به کشش بالای خود قیمتی گوشت قرمز، مرغ و تخم مرغ بعد از همه‌گیری کووید-19 پیشنهاد می‌شود برای حمایت از مصرف‌کنندگان دولت از ابزار قیمتی استفاده کند. همچنین به دلیل بالا بودن ضرائب کشش‌های متقاطع تقاضا برای گوشت قرمز، مرغ و تخم مرغ بعد از همه‌گیری کووید-19 می‌توان انتظار داشت که تغییر در قیمت یکی از محصولات گوشت قرمز، مرغ و تخم مرغ، تقاضای محصول دیگر را به گونه‌ای چشمگیر دچار تغییر کند، بنابراین، در اعمال مدیریت بهینه تقاضا و برنامه‌ریزی الگوی مصرف، استفاده از سیاست‌های قیمتی کالای جاشنین می‌تواند کارا باشد.
کلیدواژهها: تغییر ترجیحات، سیسستم تقاضای تقریبا ایده‌آل درجه دو، شکست ساختاری.
کلیدواژهها
موضوعات
عنوان مقاله [English]
Assessment of the effects of Covid-19 pandemic in the analysis of demand for livestock products using switching regression framework
نویسندگان [English]
- mahdi pendar 1
- mohammad rezvani 2
- eyed Safdar Hosseini 3
- Hamed Rafiee 4
1 Assistant Professor, Department of Agricultural Economics, Faculty of Economics and Agricultural Development, University of Tehran, Karaj,Iran
2 Ph.D student Department of Agricultural Economics
3 Professor Department of Agricultural Economics
4 Associate Professor Department of Agricultural Economics
چکیده [English]
Introduction
The economy of countries are always exposed to shocks, including the Covid-19 pandemic, which cause various problems. The epidemic of Covid-19 has had various effects and consequences in various sectors, including the agricultural sector. So that the decrease in income and production and the loss of customers according to health quarantines and border closures have severely affected the business of farmers and created many problems for activists of various sectors of the agriculture. One of the most important effects of the Covid-19 pandemic is the reduction of economic growth worldwide. This issue has resulted in to an increase in unemployment and a decrease in the people's purchasing power in the community and a decrease in demand. According to the impact of the covid-19 pandemic on food demand as a result of disorder in the supply chain and income impulses, the purpose of this research is to investigate the existence of a structural failure in the preferences of livestock products (red meat, chicken, eggs and milk) of Iranian consumers using the Quadratic almost ideal demand system and the switching regression framework developed by Ohtani & Katayama (1986) in the period of spring 2015 to winter 2022.
Materials and Methods
Nonparametric and parametric approaches are used to investigate structural failure in consumer preferences. The parametric approaches and Quadratic almost ideal demand system is employed to assess the structural failure. The switching regression framework proposed by Ohtani and Katayama (1986) is utilized to model structural changes in preferences. In fact, a time transition function enters the demand system. Based on the characteristics of demand in the literature of structural changes, Bewley likelihood-ratio test is applied to select an appropriate model.
In order to evaluate the structural failure and calculate the price and income elasticities, the price and per capita consumption data of livestock products are needed, and in this research, seasonal time series data for the period of spring 2015 to winter 2022 have been used. The information related to the price of livestock products was obtained from the Joint Stock Company of the Support of Livestock Affairs. To get the per capita consumption, first, the information on the amount of production of red meat, chicken, milk, and eggs was received from the joint stock company for livestock affairs. Then, by summing the amount of production and the amount of import of red meat, chicken, milk and eggs and deducting the amount of export from the said amount and dividing it by the population of the country, the amount of consumption per capita was calculated. The amount of export and import of red meat, chicken, milk and eggs is taken from the export and import report of the Ministry of Agriculture (Jihad), which is published monthly.
Results and Discussion
In order to estimate the system equations, one of the equations was removed and other ones were solved based the previous one, followed by estimation. Accordingly, the equation related to the removed milk and the QAIDS with 33 parameters and three equations including those related to red meat, chicken and egg were estimated using the maximum likelihood estimator non-linearly. The results show the Based on the statistics of log-likelihood and DW the existence of a gradual structural failure as a result of the Covid-19 pandemic. Comparing the statistics of Bewley likelihood ratio test calculated for an unlimited QAIDS (with structural failure) and a limited one (without structural failure) with a critical χ^2 value with degrees of freedom of nine at the probability level of 5% indicates that the unlimited QAIDS is selected as the appropriate functional one. Also, the results show that after the Covid-19 epidemic, the price of red meat and chicken has increased dramatically. Considering the high elasticity of the price of red meat, chicken and eggs after the Covid-19 epidemic, it is suggested that the government use price tools to support consumers.
Conclusion
Due to the high cross-elasticity coefficients of demand for red meat, chicken and eggs after the Covid-19 pandemic, it can be expected that a change in the price of one of the red meat, chicken and egg products will significantly change the demand for the other product. slow, therefore, in the application of optimal demand management and consumption pattern planning, the use of substitute product price policies can be useful.
Keywords: Change of Preference, quadratic almost ideal demand system, structural failure
کلیدواژهها [English]
- Change of Preference
- quadratic almost ideal demand system
- structural break
- switching regression
)
ارسال نظر در مورد این مقاله