http://hdl.handle.net/10174/150 Thu, 30 Jul 2026 02:49:29 GMT 2026-07-30T02:49:29Z http://hdl.handle.net/10174/41194 Title: Fruit and Vegetable Consumption and Happiness in the United Kingdom, Australia, and South Africa: A Fixed Effect Instrumental Variable Analysis Authors: Chao, Li-Wei; Leite, Rui; Farias, Ana Rita; Ramlagan, Shandir; Peltzer, Karl Abstract: BACKGROUND: Fruit and vegetable (FV) consumption has been linked to better physical health. Recent studies also link FV consumption to better mental health. The World Health Organization (WHO) has recommended consuming at least five servings of FV per day, but recent statistics find most populations (in both developed and developing countries) achieve far below the target, despite knowing “FV is good for health”. Two recent studies using large survey data from Australia and from the U.K. using fixed effect (FE) regression found significant and large positive associations between FV consumption and life satisfaction; the authors caution that fixed effect regression cannot show causality. METHOD AND RESULTS: Using data from the U.K., Australia, and South Africa, we apply FE and instrumental variables (IV) regressions to show that the effect of FV on life satisfaction is plausibly causal. We use the consumer price index (CPI) of FV as the instrument (F statistic > 16). We test whether controlling for individual time invariant effects was necessary, by using correlated random effects as control functions; we find that controlling for time invariant effects is not necessary for the relationship between FV and life satisfaction. We further test whether the FV variable is endogenous after controlling for FE; we find FV remains endogenous even with FE. We calculate the elasticities of FV’s effect on life satisfaction and find similar elasticities across the three countries; the increase in life satisfaction from increasing average daily FV intake by one serving would more than offset the negative effect on mental health from becoming unemployed or developing a chronic illness. To explore whether the large effect size from IV estimates is due to heterogeneous treatment effect, we apply marginal treatment effect (MTE) estimation on WHO’s five-a-day recommendation. We find that the MTE curve is downward sloped: Although some may derive large gains in marginal utility by switching from not-meeting to meeting five-a-day, others may derive little gain. Examining the potential outcomes of meeting versus not meeting five-a-day (conditioning on the individual differences in observed and unobserved resistance to meeting WHO’s guideline), we find that anyone who meets the five-a-day derives a potential high life satisfaction -- regardless of the level of resistance to eating FV. The key difference lies in the individual differences in the potential outcomes when people consume low amounts of FV. Individuals with high resistance in achieving five-a-day still have relatively high life satisfaction despite not consuming five-a-day. However, individuals with low resistance in meeting five-a-day derive very low life satisfaction had they not consumed enough FV. DISCUSSION: A public information campaign to “educate” that people will be “happy” with more FV will likely be ineffective. This is because those who derive greater happiness with more FV consumption already have low resistance to treatment and thus already consume their five-a-day. Those who do not consume five-a-day also know they are just as happy eating versus not eating five FV servings a day, so the campaign to them is irrelevant. Mon, 10 Jul 2023 23:00:00 GMT http://hdl.handle.net/10174/41194 2023-07-10T23:00:00Z http://hdl.handle.net/10174/41140 Title: Preference-Shifting Violence: Evidence From The Marikana Massacre Authors: Leite, Rui; Chao, Li-Wei Abstract: Objective: This study examines how the risk and time preferences of a sample of South African adults were affected by the Marikana massacre, a prominent episode of police violence that took place in South Africa on August 16, 2012. Previous studies have found that exposure to violence affects risk and time preferences (e.g., Voors et al., 2012; Jakiela & Ozier, 2019), but the direction of the effect is unclear. Our study contributes to this discussion and highlights a channel through which police violence – a sporadic but persistent phenomenon in many societies – can affect human decision making. Methodology: The Marikana massacre intersected fieldwork for the second wave of a large longitudinal survey being conducted in the Gauteng region, creating plausibly exogenous variation in respondents’ exposure to the event. We exploit this natural variation to estimate the causal effect of the exposure to violence on individual risk and time preferences using Pooled OLS regression models. To corroborate our findings, we examine how risk and time preferences relate to a proxy measure of interest in the Marikana massacre that is based on the intensity of internet searches for the term “Marikana”. We further test the robustness of our results by controlling for other contemporaneous events in South Africa that may act as confounding factors, and we address potential unobserved heterogeneity by re-estimating our models with individual and area-level fixed-effects. Originality: To the best of our knowledge, this study is the first to examine the impact of witnessing the Marikana massacre on risk and time preferences among South African adults. In contrast with prior research that examines long-run effects of violence on preferences or relies on retrospective recall, our design captures real-time behavioural consequences as the violent event and its aftermath unfold. We further contribute methodologically by using a measure of public salience of the event that relies on high-frequency internet search data to validate the timing-based identification strategy inherent in our natural experiment framework. Results: We find a statistically significant difference in risk and time preferences between individuals surveyed before and after the Marikana massacre, with individuals surveyed after the massacre being more risk seeking and having higher discount rates. Our pooled OLS estimates indicate that among respondents interviewed after the massacre, risk aversion and the discount rate both are higher of each standard deviation. Estimates from fixed-effects models that account for unobserved heterogeneity suggest that immediately after the massacre these effects are substantially larger. Practical implications: Out study provides strong evidence that witnessing a violent event alters risk and time preferences, two key determinants of a wide range of decisions – such as saving, investment, and health behaviour – that ultimately affect long-term welfare and development outcomes. If witnessing violence induces individuals to become more risk-averse or short-term oriented, this could reduce human capital accumulation, discourage entrepreneurship, or lead to unhealthy behaviour. From a policy perspective, our study thus highlights the broader developmental costs of police violence, and raises the possibility that such violence may contribute to widen inequality where minorities are disproportionately affected by police violence. Thu, 03 Jul 2025 23:00:00 GMT http://hdl.handle.net/10174/41140 2025-07-03T23:00:00Z http://hdl.handle.net/10174/40735 Title: Refining Sustainability Indicators for Sugarcane Production in Sofala Province of Mozambique: A Delphi Approach Authors: Viegas, Gabriel Chico; Marta, Ana; Fragoso, Rui; Cambaza, Edegar Manuel Abstract: The main objective of this article was to select a set of suitable and priority indicators to assess the sustainability of sugarcane production in the province of Sofala, in Mozambique. The Delphi method was used, and the process was conducted in two rounds with the participation of experts from academia, a sugarcane factory and government institutions. From the previous 68 indicators, a total of 38 indicators—which consisted of 9 environmental, 16 economic and 13 social indicators—were selected. Based on the priority of indicators, the following are the seven main sugarcane sustainability indicators, with 100% consensus: water availability during the entire sugarcane production process, sugarcane yield, sugarcane price, evaluation of the production based on market size and prices, sharing production risks between producers and factories, access to adequate protective equipment and wage satisfaction. Monitoring performance through these indicators can provide decision-makers with quantitative information that can contribute towards a sustainable sugarcane production system. Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/10174/40735 2025-01-01T00:00:00Z http://hdl.handle.net/10174/40690 Title: THE IMPACT OF HIGHER EDUCATION STUDENTS' MEANINGS ON UNIVERSITY QUALITY PERCEPTION IN PORTUGAL Authors: Neves, M. L.; Varela, M.; Fragoso, R. Abstract: With the expansion of Higher Education (HE) in Portugal, the student’s profiles significantly diversified (Almeida, 2007; Balsa, Simões, Nunes, Carmo, & Campos, 2001; Freitas, Martins, & Vasconcelos, 2003). Thus, in the same classroom there are students who differ in terms of previous curricular knowledge, motivations, vocational projects and maturity levels, with the addition of “non-traditional students”, which differs in their perception and expectations about the University education. In Portugal, problems associated with the transition and adaptation of new entrants may be exacerbated. To illustrate the expansion of Higher Education (HE) in Portugal , we resort to three factors that differentiate Portugal from other countries: (i) when, for reasons of the numerous clausus system in accessing higher education, about half of the students do not enter the institution and/or course of their first preference; (ii) when most students do not have parents or siblings in the family with the experience of higher education, showing a lack of information about the reality of higher education and/or presenting expectations that are too restricted or, otherwise, fanciful; and (iii) when they choose courses with less social recognition and susceptible to more easily being abandoned by work experiences that arise (Almeida, Araújo, & Martins, 2016; Alfonso-Gil et al., 2013; Alves, Gonçalves, & Almeida, 2012). Considering the evolution of higher education in Portugal the main purpose of this study is to understand the relation between the meanings attributed by higher students and their impact on perception of indicators of quality. The research methodology contemplated the following instruments and dimensions considered in the Questionnaire of significance () and the Inventory of quality in higher education students. The questionnnaire and the inventory were available in an open platform constructed with the specific purpose for this study, during the months of April until September 2022. In terms of data analysis and treatment, in this study we used the MCRLM methodology (Classic Multiple Linear Regression Model) to assess which variables significantly influence the student's perspective. In addition, the relevance of adapting and validating the Higher Education Meanings Scale: Meanings of higher education: Portuguese version of the Meaning Of Education (MOE) questionnaire (Monteiro, A. & Gonçalves, C., 2015). Given the scarcity of instruments capable of measuring the meanings that higher education students attribute to the training they attend, validation is equally relevant for those two instruments in a representative sample of Portuguese public and private higher education students after the covid-19 pandemic that devastated the world and transformed the education world it even more marked by uncertainty. The mains results explained the validation of those two instruments after the covid-19 pandemic and a positive correlations between students' meanings and the perception of qualitity of higher education institution and the dimensions of “interpersonal Learning” and “social source of stress escape”, “openness to the world”, “Self knowledge” “prepare work”, “Economic Independence”, “Next future step” Sun, 01 Jan 2023 00:00:00 GMT http://hdl.handle.net/10174/40690 2023-01-01T00:00:00Z