Integrated Parametric Graph Closure and Branch-and-Cut Algorithm for Open Pit Mine Scheduling under Uncertainty

Open pit mine production scheduling is a computationally expensive large-scale mixed-integer linear programming problem. This research develops a computationally efficient algorithm to solve open pit production scheduling problems under uncertain geological parameters. The proposed solution approach for production scheduling is a two-stage process. The stochastic production scheduling problem is iteratively solved in the first stage after relaxing resource constraints using a parametric graph closure algorithm. Finally, the branch-and-cut algorithm is applied to respect the resource constraints, which might be violated during the first stage of the algorithm. Six small-scale production scheduling problems from iron and copper mines were used to validate the proposed stochastic production scheduling model. The results demonstrated that the proposed method could significantly improve the computational time with a reasonable optimality gap (the maximum gap is 4%). In addition, the proposed stochastic method is tested using industrial-scale copper data and compared with its deterministic model. The results show that the net present value for the stochastic model improved by 6% compared to the deterministic model.

Measuring Technical Efficiency of the Smallholder Crop Farms Using Stochastic Production Frontier Approach

Agricultural productivity in Africa is the lowest in the world with many households not being able to feed themselves. In Africa, women play a major role in agriculture sector constituting about 70–80 per cent of the labour force there. Regrettably, their farm productivity is relatively low mainly due to their inefficient use of farm inputs, which has a serious implication for their socio-economic condition as well as health and nutrition status. With this backdrop in mind, the study investigated the technical efficiency (TE) of the female crop farmers in Niger Delta, Nigeria. Stochastic production frontier approach and ANOVA models were applied to analyse the primary data collected on the 216 female farmers randomly selected from 18 communities of the 3 states in the Delta. It has been found that the farm size and the quantity of labour positively influence TE of these farmers. However, farmer’s age shows a negative sign implying a decrease in technical inefficiency in age whereas the years of schooling shows a positive sign implying an increase in inefficiency with schooling thereby a resulting decrease in TE with schooling. Farm efficiency level in Delta and Akwa Ibom States was not significantly different. However, TE level in both Delta and Akwa Ibom States was significantly different from Rivers State. Since, the age of farmers showed positive influence on TE, farmers should form group and organise regular meetings to enable share knowledge and experiences on the efficient use of farm resources in the Niger Delta Region, Nigeria.

Interpreting Stochastic Frontier Model as Random Coefficient Model and Vice Versa

This note explores the relationship between the stochastic frontier model and the random coefficient regression model. It shows how to interpret the former as a special case of the latter and vice versa. JEL classification numbers: C13, C51, D24. Keywords: Stochastic production frontier, Random coefficient regression, Composite error, Technical inefficiency.

Land Tenure Systems and Agricultural Productivity in Nigeria: a Case of Rice Production

This study examined land tenure systems and rice productivity in Nigeria. Primary data were used for the study. Data were collected with the aid of a well-structured questionnaire. A four-stage sampling technique was used to select a total sample size of three hundred and forty-nine (349) rice farmers based on the number of questionnaires correctly filled and returned from the selected sampled size. Data were analyzed using descriptive statistics, total factor productivity, and Stochastic production frontier model. The study revealed that large portion of the land (over 94%) used for rice production were acquired through inheritance mode of land acquisition and communal type of land tenure system widely practiced. The result of total factor productivity indicated that 62.18% of the rice farmers were at sub-optimal productivity level. The results of the stochastic production frontier function revealed that seed (P< 0.10), and fertilizer application (P<0.01) were the significant factors influencing technical efficiency of rice production in the study area. Based on the findings, the study recommend that current land use act and policy should be amended to prevent concurrent grabbing of agricultural land for non-agricultural purposes in order to enhance availability and accessibility of land for agriculture.

Measuring Efficiency in the Summer Olympic Games Disciplines: The Case of the Spanish Athletes

This paper estimates the technical efficiency of Olympic disciplines in which Spanish athletes participate, taking into account the results obtained in the last three Olympic Games. A stochastic production frontier model (normal-exponential), using two control variables linked to economic factors such as budget and sports scholarships, is estimated in order to obtain different Olympic sports’ efficiencies distinguished by gender, using data from 2005 to 2016. The results detect some differences among the considered disciplines. In all the cases, athletics, canoeing, cycling, swimming, and tennis, depending on the gender, reach better values. This paper’s novelty lies in the efficiency analysis carried out on the Olympic disciplines and athletes of a country and not on the country’s efficiency, which allows managers and stakeholders to decide about investments concerning disciplines and athletes.

A Stochastic Frontier Approach Applied to Farms to Selected Andean Countries

In this paper, we estimate a stochastic production function for Bolivia, Ecuador, Colombia, and Peru to investigate whether road infrastructure affects farm technical inefficiency. We use agricultural censuses of Colombia and Bolivia in 2013 and 2014, respectively; national agricultural surveys in 2017 of both Ecuador and Peru; and data on the road network and travel time to the nearest town with 50,000 inhabitants or more. Our main findings are that irrigation increases the value of production and road network decreases farm technical inefficiency, that is, road density (travel time) increases (decreases) farm technical efficiency.

Economic Efficiency of Wheat Producers: The Case of Debra Libanos District, Oromia, Ethiopia

Ethiopia has enormous potential for wheat production, yet it remains a net wheat importer. This paper aims to examine the efficiency of wheat production in Debra Libanos district, Ethiopia. Two stages sampling technique was used to randomly select 150 farmers for the study. A stochastic production frontier and two-limit Tobit estimator was utilized in the study. The study reveals that technical (78.5 %,), allocative (85.6%), and economic (66.7%) efficiencies. The yield gap was 5.13 quintal/ hectare showing a room to increase efficiencies. The study identified the determinants of wheat production efficiency in the area. Hence, to improve wheat production efficiencies strengthen extension services, improved technology utilization, and proper land ploughing. Besides, natural resource conservations that improve soil fertility should be the focus of the policymakers.