Die gebruikswaarde van besluitnemingsondersteuningsmodelle vir trekkervervanging in die Vrystaat

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Date
2000-11
Authors
Coetzee, Koos
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Publisher
University of the Free State
Abstract
English: The replacement of farm tractors and availability of decision support models for assisting farmers in taking replacement decisions were studied. A literature survey, postal survey of farmers and interviews with various persons were used to gain information on the available replacement models, replacement policies, information availability and farmers' decision making processes. This information was used to model the replacement decision and develop different decision support systems. Different replacement optimising techniques were studied. Minimum-cost models are unpractical for modelling replacement decisions. An extended version of the minimum discounted cost model can be used as a decision support model for advising farmers. A simulation model for establishing replacement strategies was also developed and used to determine optimal replacement strategies. Both models indicate an economic life for tractors in excess of 10 years. An increase in the tax rate results in replacement at an earlier life than with lower tax rates.
Afrikaans: Die navorsingsprobleem wat ondersoek is, is die vervanging van landboutrekkers deur boere en die beskikbaarheid van modelle om boere in die neem van vervangingsbesluite te ondersteun. Met behulp van 'n literatuurstudie, posopname en studiebesoeke aan verskeie persone en instansies is inligting in verband met bestaande modelle, vervangingspraktyke op plase, beskikbaarheid van inligting soos in modelle benodig en die vervangingsbesluitnemingsproses van boere ingewin. Hierdie inligting is gebruik om 'n konsepsuele model van die vervangingsbesluitnemingsproses te ontwikkel. Die model het as basis vir die evaluering van beskikbare modelle en die ontwikkeling van enkele toepasbare modelle gedien. Verskeie bestaande modelle vir die bepaling van die optimale vervangingsstydstip is geevalueer. Die minimum koste-model neem net die vervangde bate in ag en is dus nie geskik vir gebruik in die evaluering van vervangingsbesluite nie. 'n Uitbreiding van die minimum koste-tegniek waar beide die vervangde en vervangende bate in ag geneem word, het wel prakties toepasbaar geblyk. Data- en tydsbehoeftes veroorsaak dat programmeringstegnieke nie prakties toegepas is nie. Verskeie veranderlikes wat op 'n vervangingsbesluit impakteer is stochasties en derhalwe is 'n simulasiemodel ontwikkel om die veranderlikes te hanteer. Beide die uniforme koste-model en die simulasiemodel dui aan dat die mees ekonomiese ouderdom om trekkers te vervang onder normale omstandighede meer as 10 jaar is. Hoë belastingkoerse lei daartoe dat trekkers veel gouer ekonomies vervang kan word.
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Keywords
Tractor, Replacement, Model, Simulation, Decision support, Repair cost, Salvage value, Reliability, Tax, Farm tractors -- Economic aspects, Farm tractors -- Cost of operation, Decision making, Thesis (Ph.D. (Agricultural Economics))--University of the Free State, 2000
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