Doctoral Degrees (Economics)

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    Socioeconomic status, economic insecurity and the obesity transition in South Africa : generational and life course aspects
    (Stellenbosch : Stellenbosch University, 2023-03) Rich, Kate Tamarin; Von Fintel, Dieter; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Economics.
    ENGLISH SUMMARY: Worldwide countries are undergoing the ‘nutrition transition’ – a shift towards diets high in saturated fat, sugar and cheap processed energy-dense foods, with a corresponding increase in rates of obesity. The rich tend to move through the transition ahead of the poor, and with this the burden of obesity tends to shift from the rich to the poor as countries develop, in a process that has been called the ‘obesity transition’. This dissertation explores several aspects of the social gradient in body weight in South Africa using the nationally representative National Income Dynamics Study (NIDS) data, proposing that changes across and between generations and over the life course may be one of the drivers of the shift from one stage of the obesity transition to the next. Chapter 2 explores the possibility that childhood socioeconomic status (SES) and intergenerational mobility may contribute to the reversal of the social gradient in body weight. I find that upward social mobility is associated with increased obesity risk in adulthood compared to individuals who maintained a stable high SES in childhood and adulthood. Furthermore, the social gradient in body mass index (BMI) is flatter among individuals from a high SES childhood background, and already appears to have reversed among women with a high childhood SES who also have a high SES in adulthood. These findings shed light on the future of the obesity transition in South Africa; they suggest that it may take more than one generation of sustained high SES – or perhaps of adequate childhood nutrition – before we see higher adult SES have a protective effect against obesity, and with it a plateau in obesity rates. Chapter 3 investigates generational aspects of the obesity transition, proposing that younger generations may be the first to see a reversal in the social gradient in body weight as they experience the benefits of upward intergenerational mobility and with it new circumstances and attitudes. I use a machine learning algorithm to find structural breaks in the social gradient in BMI by birth year. I find that the social gradient in BMI is flatter among younger cohorts of South African men, and find some indications that it is flatter among younger cohorts of women too, suggesting that the obesity transition may be driven in part by changes across generations. Chapter 4 asks whether economic insecurity is more strongly associated with body weight for those with higher levels of income, which yield increased access to excess energy. I find evidence that economic insecurity is more likely to be associated with higher BMI among higher-income women, while economic insecurity is not associated with higher BMI for men. These results suggest that, given continuing high rates of undernutrition in early life and rising living standards, obesity rates in South Africa are likely to continue to rise, particularly for those from low-SES childhood backgrounds. This calls for policies to attempt to reduce consumption of unhealthy foods, and to improve nutrition in childhood – particularly in the earliest years of life.
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    Measuring enrolment and support for children with disabilities at the school level
    (Stellenbosch : Stellenbosch University, 2023-03) Deghaye, Nicola; van der Berg, Servaas; Hanass-Hancock, Jill; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Economics.
    ENGLISH SUMMARY: The overall purpose of this dissertation was to critically assess how disability inclusion in schools is and should be measured in South Africa and to develop and report on new measures of disability inclusion. Measurement of school-reported enrolment of learners with disabilities and inputs, processes and enablers of disability-inclusion in mainstream (ordinary) schools is considered. Despite the development of inclusive education policy in post-apartheid South Africa, implementation of disability inclusion in mainstream schools has been poorly documented and disability-related educational inequalities have persisted. Very few quantitative studies have addressed teacher training for inclusion, physical accessibility of schools, accessibility of learning materials or availability of disability support structures in mainstream schools in low- and middle-income countries (LMICs). This study develops new indicators of these aspects of disability inclusion and employs them in a nationally-representative school survey. A comprehensive analysis of school-reported enrolment of learners with disabilities was conducted to determine the reliability of disability-disaggregated enrolment data. The analysis demonstrates that school-level data on enrolment of learners with disabilities collected in annual surveys was inconsistent over time and incomplete and produce estimates that are much lower than rates of disability prevalence among learners estimated from household surveys. School reporting has, however, become more complete following the introduction of a learner-level Education Management Information System (EMIS). This study demonstrates that ordinary schools in South Africa have no financial incentive to enrol or report the presence of learners with disabilities. The importance of question wording when eliciting data on disability status has been demonstrated by previous research. This study demonstrates that the disability questions used in the EMIS in South Africa are not aligned with current education policy nor with the biopsychosocial model of disability. It recommends that the questions on disability status in EMIS are aligned with those used in the screening and identification processes used in schools since 2014. Multivariate analysis was used to show that schools in wealthier areas of South Africa are more likely to report enrolment of learners with disabilities than schools in more deprived areas. This suggests that schools in less wealthy areas experience greater difficulty identifying or reporting learner’ disability status. This has resulted in skewed reporting of disability-disaggregated enrolment by school wealth quintile. New (or improved) indicators of disability inclusion were developed and added to the School Monitoring Survey (SMS) 2017 (a nationally-representative sample of approximately 2,000 schools). The analysis was supplemented by a qualitative follow-up study examining ease of use of the teacher questionnaire. The improved indicators provide more comprehensive evidence on the proportion of schools that are physically accessible, have disability support structures in place, and where teachers have received training in inclusive education. These factors are critical in enabling ordinary schools to provide reasonable accommodation of learners’ individual needs. This study uses multivariate analysis to show that prior training is associated with improved teacher confidence in addressing learning barriers. This is the first study to use multivariate analysis of the SMS in relation to disability-inclusion. This study provides the first set of comparable nationally-representative data on disability inclusion at two time points. It shows that some progress has been made over time but that substantial provincial inequality across several indicators of disability inclusion remains. The performance of full-service schools is compared to that of ordinary schools in SMS 2017. A large, fairly-representative sample of full-service schools is shown to perform better than ordinary schools in various aspects of disability inclusion, but still fall short of the expectations in current guidelines. This study results in a much more comprehensive depiction of disability inclusion in ordinary schools than has been achieved by previous studies. It adds substantially to the body of evidence on operationalising the biopsychosocial model of disability in school indicators in middle-income countries.
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    Socioeconomic status and chronic diseases in South Africa
    (Stellenbosch : Stellenbosch University, 2022-12) Gangaidzo, Trust; Burger, Ronelle; Von Fintel, Marisa; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Economics.
    ENGLISH SUMMARY: The global burden of non-communicable diseases (NCDs) is on the rise, and is expected to increase. The United Nations, through the 2030 Agenda for Sustainable Development Goals, acknowledged the public health importance of addressing NCDs, and set a goal to reduce premature mortality from NCDs by one-third by 2030. Key to achieving targets for prevention and control of NCDs is a holistic approach to understanding the underlying contextual causes. This thesis examines the role of inequality in socioeconomic status in the development of chronic diseases in South Africa, a highly unequal middle-income country battling communicable diseases and maternal and child mortality. To achieve this, the study had three objectives: (1) To examine how exposure to negative household events and neighbourhood characteristics relates to systolic blood pressure in South Africa; (2) To determine socioeconomic factors that explain depressive symptoms in South Africa; and (3) To ascertain the influence of the COVID-19 pandemic on income-related inequality in depressive symptoms in South Africa. The study is presented in three essays. In the first essay, I estimate the relationship between systolic blood pressure and exposure to stressful (negative) household events and neighbourhood characteristics. Using the correlated random effects model, I found that systolic blood pressure is significantly higher among respondents from households that had registered the death of a household member and those that reported a reduction in grant income and remittances. The direct effects of neighbourhoods were related to neighbourhood income level, whereby moving from a low-income neighbourhood to a middle-income neighbourhood was negatively associated with systolic blood pressure. With regard to the heterogenous effects of neighbourhoods, I found a negative and significant mean-level “job loss” effect. The implications of the study results are vast in a country like South Africa, which is already burdened with high mortality due to causes such as human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) and tuberculosis (TB), injury and homicide, and NCDs such as cardiovascular diseases and diabetes. In the second essay, I examine the relationship between depressive symptoms and socioeconomic factors using the ordinary least squares model and the fixed effects model. Results from both models suggest significant socioeconomic gradients in depressive symptoms, whereby depressive symptoms are negatively associated with per capita household income, education, and social capital. However, I found a positive and significant association between depressive symptoms and unemployment only in men. The significant differences in the effects of variables by gender and by residence are a unique contribution to understanding the differences in health in South Africa, and may inform policies. Firstly, there are significant gender- and residence profiles in depression. Secondly, men who self-report good health may overestimate their health, most likely by excluding their state of mental health. Lastly, whilst the goal is to reduce the prevalence of mental disorders by targeting socioeconomic factors, differences by gender and residence underscore the need for mental health policies that promote equity. As reported in the third essay, I used a recentred influence function regression decomposition method developed by Heckley et al. (2016) to ascertain the influence of the COVID-19 pandemic on inequality in depressive symptoms related to income in South Africa. I found that the COVID-19 pandemic negatively and significantly influenced income-related inequality in good mental health in South Africa. This means that the COVID-19 pandemic disproportionately increased mental health problems amongst the affluent. I did not find an education profile in the joint distribution of income and mental health. Self-reported health-, age-, population group-, and gender profiles were present in the covariance between Income and good mental health. I used publicly available longitudinal data from the South African National Income Dynamics Survey in the study. Overall, the findings of this study suggest that socioeconomic factors contribute to the rising burden of chronic diseases in South Africa. Notwithstanding the study’s limitations, this thesis makes a significant contribution to understanding the typical mechanisms and pathways through which poverty and chronic conditions interact and reinforce each other in South Africa, and other low- to middle-income countries. This, in turn, provides useful inputs for policy and programmes to address the burden of chronic conditions in poor societies. Whilst pharmacological and medical technology advancements are important in extending life expectancy, socioeconomic interventions are equally important in curbing both rising morbidity and mortality from chronic diseases, and in addressing poverty and inequalities in low- to middle-income countries. Unlike physiological causes, socioeconomic determinants of health can be influenced through health- and government policy interventions, which could also be justifiable in terms of efficiency and equity.
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    An assessment of malaria prevention, diagnosis and treatment services in Uganda
    (Stellenbosch : Stellenbosch University, 2022-04) Kimbugwe, Hassan; Burger, Ronelle; Matovu, Fred; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Economics.
    ENGLISH SUMMARY: Government, donor partners, and the private sector invest large amounts of financial resources annually in malaria prevention and care. Despite substantial spending on malaria prevention programmes by 2019/2020, the disease still accounted for 13.3% Uganda's mortality, as well as 29.8% of outpatient visits and 34.9% of inpatient admissions. To combat malaria more effectively, it is critical to understand whether these substantial investments in malaria prevention and care reach those who are most vulnerable to malaria, and whether approved malaria diagnosis and treatment protocols are followed diligently. This PhD was thus structured to consider three distinct but related issues: (i) the equity of bed net use and ownership in 2009 and 2014, (ii) the uptake of malaria prophylaxis amongst pregnant women, and (iii) the relationship between financial incentives and appropriate malaria diagnosis and case management. The first essay examines the equity in access to and utilisation of bed nets in 2009 and 2014. It was found that the availability of bed nets increased over time. Access to and use of bed nets became more equitable, with higher levels of access and use amongst poorer households. Households with access to at least one bed net rose from 59.2% to 94.1%. The percentage of households who slept under bed nets increased from 51.8% to 72.6%. The percentage of children under five years who slept under bed nets increased from 45.8% to 81.5%. The percentage of pregnant women who slept under bed nets increased from 78.6% to 83.8%. Through recentered influence functions (RIF) decomposition method, the study examined whether the demographic factors were associated with the relationship between the wealth index and bed net utilisation in 2009 and 2014. Results suggest that in 2009, place of residence, number of nets in a household, mother’s education level, region and household size were associated with the relationship between wealth index and bed net utilisation. In 2014, age of household members, and mother’s education level were associated with the relationship between the wealth index and bed net utilisation. In both years having a mother with at least primary level of education was vital in promoting bed net utilisation. The results further indicate that younger household members, women, household members from the northern region, household members from the poorest wealth quintile, mothers with a post-secondary education, and households with more bed nets and few members were more likely to sleep under bed nets in 2014. The second essay reviews factors associated with uptake of intermittent preventive treatment (IPT) of three doses of Sulfadoxine-pyrimethamine (SP) (IPT-SP3) during pregnancy. The analysis indicated a double and notable improvement in uptake over time, from 9.91% in 2011 to 17.89% in 2016. However, the uptake was still far below the 79% target of Uganda’s Health Sector Strategic Plan (Uganda Ministry of Health (MoH) 2014). Results showed that uptake was higher amongst younger women (under the age of 25 years) than older women (above the age of 34 years), higher amongst women who attended their first antenatal care (ANC) visit early (during the first trimester) than those who attended later (during the third trimester), higher amongst women from the upper wealth quintile than women from the poorest quintile, and higher amongst women from the northern region of Uganda than among women from the central region. Results also indicated that uptake of IPT-SP3 was lower amongst women from the western region than women from the central region. Findings from the pooled model (unrestricted) indicate that the relationship between IPT-SP3 and the covariates in the two different time period (2011 and 2016) have not changed. The third and final essay focuses on the relationship between financial incentives and the likelihood of private providers adhering to national guidelines on malaria diagnosis and dispensing practices. The specific concern is that volume or revenue-based staff remuneration may provide a strong incentive for provision of malaria drugs to patients who have not yet tested for malaria. This tension is observed in a subsample where facilities do not have malaria testing capabilities and only sell malaria treatment and staff are paid based on the volume of drugs sold or the revenue. The results suggest that the private healthcare providers who receive salaries are more likely to adhere to malaria treatment protocols. Descriptive findings indicate significant variations between drug-shop attendants and other private healthcare providers with regard to malaria diagnosis, antimalarial dispensing practices, and adhering to malaria treatment procedure.
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    Bargaining competition and vertical mergers
    (Stellenbosch : Stellenbosch University, 2022-04) Minnie, Roan Johan; Boshoff, Willem Hendrik; Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Economics.
    ENGLISH SUMMARY: Vertically related markets and vertical mergers are complex systems that comprise a number of distinct features. The modelling of such complex systems involves several modelling choices that affect the predicted model outcomes. We rely on simulation-based methods to consider how choices of key model parameters, assumptions and industry structures map onto competitive outcomes in vertically related markets and for vertical mergers. Our simulation results can help guide practitioners in selecting models that best characterise the features of a given vertical relationship, especially since assumptions that distinguish the models from one another — how and over what parties bargain — are typically not observed. In particular, this dissertation studies vertically related markets and vertical mergers along three dimensions. Firstly, we focus on comparing alternative models of vertical competition, based on different assumptions regarding the nature and object of vertical contracting. As far as the nature of vertical contracting is concerned, models may assume upstream and downstream firms reaching agreement through take-it-or-leave-it offers, bargaining or recursive bargaining. As far as the object of vertical contracting is concerned, models may assume vertical contracting is over linear prices (a marginal wholesale price) or two-part prices (a marginal wholesale price and a fixed f ee). We systematically compare the corpus of models of vertically related markets across two simple industry structures (‘1 _ 2’, one upstream and two downstream firms; and ‘2_1’, two upstream and one downstream firm) to allow direct comparisons. Our comparisons show that in a linear pricing setting, a modelling choice between bargaining and recursive bargaining is irrelevant to the outcome. In two-part pricing, however, bargaining leads to a more competitive outcome than the joint profit maximising outcome under recursive bargaining. Secondly, we study and compare models for vertical merger analysis, in order to investigate how assumptions regarding vertical contracting map onto observable merger effects. We also examine the extent to which predictions from models of vertical mergers are robust to different specifications of substitutability. In particular, we compare models calibrated to an increasing aggregate elasticity (i.e. the substitutability of the inside goods with the outside good) with models calibrated to the nest strength parameter of the demand function. Our results show that the predicted merger effects from different models are consistent for the two measures of substitutability. The results also illustrate that modelling choices such as the specification of the industry structure or object and nature of vertical contracting that determined outcomes in the pre-merger world, can also predetermine post-merger outcomes. Lastly, we introduce a vertical merger simulator tool to allow an assessment of vertical merger scenarios in practice. We illustrate the utility of the simulator as a screening tool by reference to a number of examples reflecting modelling choices often faced by practitioners. In this regard, we illustrate three examples where the exogenous variables of interest are the marginal cost of the upstream firm and downstream firms, the market shares and the prices of the downstream firms respectively. We compare the simulator to incentive scoring methods (comprising of various upward pricing pressure indices), which have received extensive attention in literature and policy circles as a screening tool for merger effects, including for vertical mergers. While direct comparisons are challenging, it is evident that the data requirements of our vertical merger simulator are not particularly onerous compared to those of incentive scoring indices. The simulator offers the additional benefit of full equilibrium analysis, compared to the partial equilibrium focus of incentive scoring methods. We conclude that the simulator can be a useful complementary tool for vertical merger screening.