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ThesisItem Open Access Time series intervention modeling and simulation for mustard yield forecasting in Haryana(CCSHAU,HiSAR, 2020-10) Ajay Kumar; Verma, UrmilModeling and Simulation is a discipline for developing a level of understanding of the interaction of the parts of a system, and of the system as a whole. A model is a simplified representation of a system at some particular point in time or space intended to promote understanding of the real system. Simulation permits the evaluation of operating performance prior to the implementation of a system. The study compares the efficacy of time series Intervention models and simulation in quantifying the pre-harvest mustard yield in Hisar, Bhiwani, Sirsa, Fatehabad, Mahendragarh, Rewari, Jhajjar and Gurugram districts of Haryana. The objective of this study was to assess the forecast accuracy of the contending models for district-level mustard yield forecasts in Haryana. The fortnightly weather data on rainfall, minimum temperature and maximum temperature over the crop growth period (September-October to February-March) have been utilized from 1980-81 to 2010-11 for the models‟ building. The weather-yield data from 2011-12 to 2015-16 have been used to check the post-sample validity of the fitted models for mustard yield forecasts in comparison to those obtained from State Department of Agriculture crop yield(s) estimates. The statistical modeling approaches viz., multiple linear regression, ARIMA, regression with ARIMA errors (RegARIMA) and ARIMA-Intervention were applied for the purpose. First of all, weather-yield models based on multiple linear regression were developed to relate mustard yield to fortnightly weather input alongwith linear time-trend yield/crop condition term as an indicator variable.Alternatively, ARIMA, RegARIMA, and ARIMA-Intervention models were fitted as per targeted objectives. Additionally, Student‟s t-copula in SAS is applied as a simulation tool and compared the output to the time series forecasts. The forecasts are compared to determine if there is either a consistent or significant difference between the two output. The forecast performance(s) of the alternative models were observed in terms of percent relative deviations of mustard yield forecasts from observed yield(s) and root mean square error(s). RegARIMA models performed well with lower error metrics as compared to the alternative models in most of the time regimes. Five-steps ahead forecast figures i.e. 2011-12 to 2015-16 favour the use of RegARIMA models to obtain pre-harvest mustard yield forecasts in the districts under study. The forecasts generated by RegARIMA are remarkably close to the forecasts obtained through the simulation process. Empirical evidence from this study confirms that the RegARIMA model can produce reliable forecasts and would therefore provide a more robust approach of forecasting with limited data sets.using the developed forecast models, the district-level mustard yield estimates could be computed successfully well in advance of the actual harvest. On the other hand, the State Department of Agriculture crop yield estimates are obtained quite late after the actual crop harvest.
