مدلسازی وابستگی بین قیمت تضمینی و تولید چغندر قند در ایران با در نظر گرفتن عوامل اقلیمی: کاربرد رویکرد کاپولا و فرآیند گاوسی
محورهای موضوعی : تغذیه
سپیده عظیمی
1
,
سعید کیان پور
2
,
رضا شمس اللهی
3
1 - مربی،گروه علوم پایه، دانشگاه ملی مهارت، تهران، ایران.
2 - عضو هیات علمی گروه اقتصاد/دانشگاه پیام نور
3 - دانشجوی دکتری اقتصاد، دانشکده اقتصاد و حسابداری، دانشگاه رازی ، کرمانشاه، ایران
کلید واژه: قیمت تضمینی, چغندر قند, عوامل اقلیمی, رویکرد کاپولا, فرآیند گاوسی,
چکیده مقاله :
این مطالعه با هدف مدلسازی وابستگی بین قیمت تضمینی و تولید چغندر قند در ایران با در نظر گرفتن عوامل اقلیمی (بارش و دما) طی دوره ۳۵ ساله (۱۳۶۸-۱۴۰۲) و برای مدلسازی وابستگیهای غیرخطی، از رویکرد کاپولا گاوسی (با تخمین τ کندال) و فرآیند گاوسی با کرنل RBF استفاده شد. مدل جنگل تصادفی برای تحلیل اهمیت ویژگیها و الاستیسیتهها به کار رفت. نتایج نشان داد تولید چغندر قند (ضریب تغییرات ۲۷.۲%) به دما (الاستیسیته ۰.۳۹-) حساستر است تا قیمت (الاستیسیته ۰.۲۱) و بارش (الاستیسیته ۰.۰۳۳-). رابطه دما و تولید غیرخطی (معکوس U شکل) بوده و تولید در دمای ۲۳-۲۷ درجه سانتیگراد به بیشینه میرسد. شاخص پایداری تولید (۰.۷۲۸) ثبات نسبی تولید را نشان داد، اما CV_R² منفی احتمال اورفیتینگ را مطرح کرد. یافتهها بر ضرورت ترکیب سیاستهای قیمتی با مدیریت اقلیمی و فناوریهای مقاوم به گرما و خشکی تأکید دارند. محدودیتهای مطالعه شامل استفاده از دادههای ملی و قیمتهای اسمی است. پیشنهاد میشود تحقیقات آینده از دادههای منطقهای و مدلهای پویا استفاده کنند.این مطالعه با هدف مدلسازی وابستگی بین قیمت تضمینی و تولید چغندر قند در ایران با در نظر گرفتن عوامل اقلیمی (بارش و دما) طی دوره ۳۵ ساله (۱۳۶۸-۱۴۰۲) و برای مدلسازی وابستگیهای غیرخطی، از رویکرد کاپولا گاوسی (با تخمین τ کندال) و فرآیند گاوسی با کرنل RBF استفاده شد. مدل جنگل تصادفی برای تحلیل اهمیت ویژگیها و الاستیسیتهها به کار رفت. نتایج نشان داد تولید چغندر قند (ضریب تغییرات ۲۷.۲%) به دما (الاستیسیته ۰.۳۹-) حساستر است تا قیمت (الاستیسیته ۰.۲۱) و بارش (الاستیسیته ۰.۰۳۳-). رابطه دما و تولید غیرخطی (معکوس U شکل) بوده و تولید در دمای ۲۳-۲۷ درجه سانتیگراد به بیشینه میرسد.
This study aimed to model the dependence between guaranteed price and sugar beet production in Iran considering climatic factors (rainfall and temperature) over a 35-year period (1402-1368). To model nonlinear dependencies, the Gaussian Copula approach (with Kendall's τ estimation) and the Gaussian process with RBF kernel were used. The random forest model was used to analyze the significance of features and elasticities. The results showed that sugar beet production (coefficient of variation 27.2%) was more sensitive to temperature (elasticity -0.39) than price (elasticity 0.21) and precipitation (elasticity -0.033). The relationship between temperature and production was nonlinear (inverted U-shaped) and production reached a maximum at 23-27°C. The production stability index (0.728) showed relative production stability, but the negative CV_R² suggested the possibility of overfitting. The findings emphasize the necessity of combining price policies with climate management and heat and drought resistant technologies. Limitations of the study include the use of national data and nominal prices. It is suggested that future research use regional data and dynamic models.This study aimed to model the dependence between guaranteed price and sugar beet production in Iran considering climatic factors (rainfall and temperature) over a 35-year period (1402-1368). To model nonlinear dependencies, the Gaussian Copula approach (with Kendall's τ estimation) and the Gaussian process with RBF kernel were used. The random forest model was used to analyze the significance of features and elasticities. The results showed that sugar beet production (coefficient of variation 27.2%) was more sensitive to temperature (elasticity -0.39) than price (elasticity 0.21) and precipitation (elasticity -0.033). The relationship between temperature and production was nonlinear (inverted U-shaped) and production reached a maximum at 23-27°C.
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