Browsing by Subject "Operations Research in Development"
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- ItemOpen AccessAiding Decision making for foodbank Cape Town(2010) Blake, Timothy James; Stewart, Theodor J; Van Dyk, Esbeth
- ItemOpen AccessModeling of Spaza shop operations using soft and hard operational research techniques(2009) Sabwa, Jean-Marie; Stewart, Theodor JGlobalization has transformed the world into a big village in which the rich are becoming richer and the poor getting poorer. In the commercial world the trend is for big business to buy out the smaller companies and consequently get bigger. Yet it is arguable that small businesses have assisted in providing much needed services to small communities that occupy informal settlements and exist on or below the poverty datum line. The South African government has amongst its main objectives the alleviation of poverty and the improvement of life in previously disadvantaged communities. The government has allowed the micro-enterprises and small businesses in the informal sector to thrive and in this sector are Spaza shops that supply a wide range of grocery commodities to informal settlements. This paper is about an application framework of soft and hard operational research (OR) techniques used to address the performance of micro-enterprises with Spaza shops in Western Cape as a specific case study. The techniques include Strategic Options Development and Analysis (SODA) using Causal mapping and Soft System Methodology (SSM). These were chosen because of their suitability to understand performance problems faced by Spaza shops owners and find ways of improving the current situation by modelling the intervention of stakeholders. The improvement of Spaza shop businesses is a matter for all stakeholders. Causal mapping, helped to identify and structure the multiple conflicting aspects of Spaza shops business. Soft System Methodology made it possible to conceptualize the intervention model based on the rich picture and root definitions for relevant world-views and see what changes are culturally feasible and systematically desirable. Computer simulations were used to help design and test performance measurement indicators for the Spaza shops so as to enable decision-makers to choose the optimal strategy. Statistical analysis came into account to enable us to capture the seasonality and bring up clustering patterns.
- ItemOpen AccessA simulation model of antimalarial drug resistance(2009) Silal, Sheetal Prakash; Little, Francesca; Stewart, Theodor JMalaria ranks among the world's most important tropical parasitic diseases with world prevalence figures between 350 and 550 million clinical cases per annum. [WHO, 2008a] 'Treatment and prevention of malaria places a considerable burden on struggling economies where the disease is rampant. Research in malaria does not stop as the change in response to antimalarial drug treatment requires the development of new drugs and innovation in the use of old drugs. This thesis focused on building a model of the spread of resistance to Sulfadoxine/Pyrimethamine (SP) in a setting where both SP and SP in artemisinin-based combination therapy (ACT) are the first line therapies for malaria. The model itself is suitable to any low transmission setting where antimalarial drug resistance exists but the country of choice in this modeling exercise was Mozambique. The model was calibrated using parameters specific to the malaria situation in Mozambique. This model was intended to be used to aid decision making in countries where antimalarial drug resistance exists to help prevent resistance spreading to such an extent that drugs lose their usefulness in curing malaria. The modeling technique of choice was differential equation modeling; a simulation technique that falls under the System Dynamics banner in the Operations Research armamentarium. It is a technique that allowed the modeling of stocks and flows that represent different stages or groupings in the disease process and the rate of movement between these stages respectively. The base model that was built allowed infected individuals to become infectious, to be treated with SP or ACT and to be sensitive to or fail treatment. Individuals were allowed a period of temporary immunity where they would not be reinfected until the residual SP had been eliminated from their bloodstream. The base model was then further developed to include the pharmacokinetic properties of SP where individuals were allowed to be reinfected with certain strains of infection given the level of residual drug in their bloodstream after their current infection had been cleared. The models used in this thesis were built with idea of expanding on previous models and using available data to improve parameter estimates. The model at its core is similar to the resistance model used in Koella and Antia [2003] where differential equation modeling was used to monitor a population as it became infected with a sensitive or resistant infection and then University of Cape Town recovered. The inclusion in the model of the PK component was derived from Prudhomme-O'Meara et al. [2006] where individuals could be reinfected depending on the residual drug in their bloodstream. Rather than modeling simply sensitive and resistant infections, mutations categories were used as was the case in Watkins et al. [2005] population genetics model. The use of mutation categories allowed one to use parameters specific to these categories rather than the sensitive/resistant stratification and this is particularly relevant in Mozambique where all mutation categories still exhibit some degree of sensitivity to treatment i.e. total resistance has not yet developed for any particular mutation category. The last adaptation of the model was to use gametocyte information directly to determine human infectiousness rather than through using a gametocyte switching rate (constant multiplier used to convert parasite density to gametocyte density) as was done in Pongtavompinyo [2006]. The models developed in this thesis found that the existing vector control and drug policy in Mozambique had the major effect of decreasing total prevalence of malaria by approximately 70% in the 11 year period. The distribution of Res3 (presence of DHFR triple) and Res5 (presence of DHFR triple and DHPS double) infections changed over the 11 year period with Res3 infections initially increasing and then decreasing while Res5 infections started low and increased to overtake Res3 infections. The timing of the change in this composition of infection corresponds with the introduction of ACT and thus it appears that the use of ACT prompted the increased prevalence of quintuple parasites over DHFR triple and sensitive parasites. The total number of failures decreased substantially after the introduction of ACT to 17% of its previous level. The results of the base model corresponded with the observed data from the SEACAT study in terms of the magnitude and the trends of the impact of the change to ACT policy, but underestimated the impact of the vector control strategies compared to rapid effect noted in Sharp et al. [2007]. The Scenario testing of the base model showed that vector control is an effective strategy to reduce prevalence and that it is sensitive to the time at which the control is started as it decreased prevalence very gradually. The Scenario testing of the base model also showed that the introduction of ACT in Mozambique had a greater impact on reducing prevalence and that the start time of the ACT strategy did not decrease the effect on prevalence though earlier start times decreased the total number of resistance cases. The ratio of Res5 to Res3 infections increased faster when ACT was the treatment policy than when SP was the policy. Thus higher values of this ratio are associated with ACT being the treatment strategy in place. Thus differential equation modeling is an effective modeling tool to capture the spread of disease and to test the effects of policy interventions as it allows one to assess these effects on populations and averages out individual-level intricacies to better inform policy decisions.
- ItemOpen AccessThe use of data mining as a decision making tool for municipal performance management in the Western Cape(2007) Rasmussen, Erica L; Scott, Leanne; Stewart, TheodorThis thesis proposes the use of data mining tools within an operations research process, allowing the integration of ever increasing amounts of data collected worldwide. It is further argued that the wealth of information delivered by DM tools, with their strong visual emphasis, can be used by enhance the transfer of knowledge of stakeholders. The discipline of operations research could benefit greatly from the methods offered within the field of data mining, used to analyse the ever increasing amounts of data collected worldwide. However, the subject also offers a wealth of information that could aid in decision making, along with visual representations of this information that might assist in the transferral of knowledge to problem stakeholders. The advantages offered by data mining are not limited to problem contexts containing high-quality data, but could also assist within the development contexts containing high-quality data, but could also assist within the development context where traditionally resources and relevant skills are scarce. The benefits of data mining within this context are illustrated through the use of municipal performance data supplied by the Department of Local Government and Housing in the Western Cape of South Africa. The results of these analyses are presented to the department in order to assess the potential contribution of data mining to decisions surrounding municipal support.
- ItemOpen AccessThe use of problem structuring methods to explore the functioning and management of a selected NGO(2007) Anyogu, Alexander A; Scott, Leanne; Stewart, TheodorPoverty eradication is one of the major challenges facing South Africa and the rest of the continent. Concern around poverty alleviation in South Africa encompasses lack of capacity as well as inefficiency in the management and administration of poverty alleviation projects. Therefore, poverty alleviation agencies ought to be mindful of the issues that could affect their organizational efficiency, especially issues around organizational management. Addressing issues of management amongst the poverty alleviation agencies is necessary to assist role players in the implementation of efficient and effective poverty alleviation programs. The research explored issues around the management structure of a selected non-government organisation (SHAWCO). The objective was to develop a shared understanding of the organizational structure, amongst the members of the management team, and identify (if any) inefficiencies within the structure of the organisation. Problem Structuring Methods have been identified as a collection of tools that assist decision makers in addressing complex societal problems, and seek to alleviate or improve situations characterized by uncertainty, conflict and complexity. The study used Problem Structuring Methods to investigate the possible difficulties SHAWCO is facing as a result of management inefficiency. Interviews were used to uncover issues around the functioning and management of the organization, and an interactive problem structuring workshop was later conducted to develop a shared understanding of the identified issues.