Дисертації з теми "Collective and individual risk"

Standard finance theory portrays investors as rational utility maximisers. Persisting market anomalies and observed investor practice, however, have led to widespread recognition that the fundamental axioms of rationality are often violated. In response to the limitations inherent in standard theory, the Behavioural Finance approach relaxes the rationality assumption and takes account of psychological influences on individuals’ decision-making processes. Adopting the behavioural approach, this thesis, which includes two empirical studies, examines why, and to what extent, investors depart from rational or optimal investment practices. The thesis examines the effect of Myopic Loss Aversion (MLA) suggested by Benartzi and Thaler (1995) as a response to the Equity Premium Puzzle highlighted by Mehra and Prescott (1985). While previous studies are almost exclusively based on experiments in a laboratory setting, this approach provides more compelling empirical evidence by investigating the effects of MLA on real individual investors’ portfolio allocations through the use of the Dutch National Bank Household Survey. For the first time, the concept of MLA is identified through the interaction of two separate effects, firstly, individuals’ myopia, reflected in portfolio evaluation and rebalancing frequencies, and secondly, loss aversion. The thesis finds that individuals who are less affected by MLA invest more in risky financial assets. Further, individuals who are less myopic increase their share of risky assets invested in their financial portfolios over time, although this is unrelated to their loss aversion. These findings support the prediction of MLA theory that short investment horizons and high loss aversion lead to a significantly lower share of risky investments. In summary, the high equity premium can be explained by the notion of MLA. If individuals evaluate their investment performance over the long-term, they perceive much smaller risks relative to stockholding returns; consequently, they will be prepared to accept smaller equity premiums. The findings suggest possible interventions by policy makers and investment advisors to encourage individuals to remain in the stock market, such as providing long-term investment instruments, or restricting evaluation frequency to the annual reporting of investment performance. In response to the stockholding puzzle (Haliassos and Bertaut, 1995), this thesis also investigates individuals’ stock market returns expectations and their varying levels of risk aversion. Previous studies find that individuals’ heterogeneous stock market expectations determine variations in their stockholdings. The thesis accounts for the effect of risk aversion on stock market expectations, as well as on stockholding decisions. Additionally, the causality issue as between individuals’ expectations and stockholding status is controlled. The thesis finds that more risk averse individuals hold lower stock market expectations, and that the stock market return expectations of more risk averse individuals affect their stock market participation decisions negatively. The portfolio allocation decisions of individuals who already hold stocks are only affected by their expectations, with risk aversion being no longer significant. The thesis argues that persistent risk aversion effects cause individuals to hold pessimistic views of stock market returns, thus contributing to the enduring stockholding puzzle. The thesis reinforces existing perceptions that individuals in the real world may not make fully rational decisions due to their judgments which are based on heuristics and affected by cognitive biases. Individual investors often fail to maximise their utility given their preferences and constraints. Consequently, this thesis draws attention to the possible role of institutions, policy makers, and financial advisory bodies in providing effective interventions and guidelines to improve individuals’ financial decisions.

The aim of the present research is to advance a general predictive model of the social psychological processes underlying collective action in contexts where collective action is met with significant repression by the authorities. The model integrates the recent advancements in the collective action literature and examines the unique predictive role of anger and fear (emotional pathway), political, identity consolidation and participative efficacies (instrumental pathway), politicised identification (identity pathway) as well as moral obligation, over and above past participation. Moreover, the research investigates how perceived risk, due to government sanctions, shapes these antecedents and the willingness to engage in collective action. Five survey studies (Studies 1 to 5) test this model in various repressive contexts (i.e., Egypt, Hong Kong, Russia, Ukraine, and Turkey). In addition, one experimental study (Study 6) examines the causal relation between perceived risk and (a) the antecedents of collective action and (b) the action intentions in a British sample. The results confirm the intensifying role of perceived risk, whereby it indirectly spurs further resistance through shaping the antecedents of collective action. The results also suggest that protesters are intrinsically motivated to engage in collective action when placed under risk. Specifically, although not motivated by political efficacy, protesters are strategic as they are motivated by the likelihood to consolidate the identity of their protest movement and the likelihood of their own participation to incrementally contribute to achieving the desired goals. Moreover, they are emotional, politicised and dutiful as their outrage towards how the authorities treat the protesters, their identification with their protest movement, as well as their sense of moral responsibility encourage them to take action despite the risks.

The data revolution experienced by social science has revealed complex patterns of interactions in human dynamics, such as the heterogeneity and burstiness of social contacts. The recently uncovered temporal dimension of social interactions calls for a renewed effort in analysis and modeling of empirical time-varying networks. This thesis contributes to pursue this program, through a twofold track: The modeling of dynamical social systems and the study of the impact of temporally evolving substrates on dynamical processes running on top of them. Firstly, we introduce some basic concepts and definition of time-varying networks formalism, and we present and analyze some empirical data of face-to-face interactions, discussing their main statistical properties, such as the bursty dynamics of social interactions. The main body of the exposition is then split into two parts. In the first part we focus on the modeling of social dynamics, with a twofold aim: reproduction of empirical data properties and analytic treatment of the models considered. We present and discuss the behavior of a simple model able to replicate the main statistical properties of empirical face-to-face interactions, at different levels of aggregation, such as individual, group and collective scales. The model considers individuals involved in a social gathering as performing a random walk in space, and it is based on the concept of social "attractiveness": socially attractive people (due to their status or role in the gathering) are more likely to make people stop around them, so they start to interact. We also devote attention to the analytic study of the activitydriven model, a model aimed to capture the relation between the dynamics of time-varying networks and the topological properties of their corresponding aggregated social networks. Through a mapping to the hidden variable model, we obtained analytic expressions for both topological properties of the time-integrated networks and connectivity properties of the evolving network, as a function of the integration time and the form of the activity potential. In the second part of the thesis we study the behavior of diffusive processes taking place on temporal networks, constituted by empirical face-to-face interactions data.We first consider random walks, and thanks to different randomization strategies we introduced, we are able to single out the crucial role of temporal correlations in slowing down the random walk exploration. Then we address spreading dynamics, focusing on the case of a simple SI model taking place on temporal networks, complemented by the study of the impact of different immunization strategies on the infection outbreak. We tackle in particular the effect of the length of the temporal window used to gather information in order to design the immunization strategy, finding that a limited amount of information of the contact patterns is sufficient to identify the individuals to immunize so as to maximize the effect of the vaccination protocol. Our work opens interesting perspectives for further research, in particular regarding the possibility to extend the time-varying networks approach to multiplex systems, composed of several layers of interrelated networks, in which the same individuals interact between them on different layers. Empirical analysis of multiplex networks is still in its infancy, indeed, while the data mining of large, social, multi-layered systems is mature to be exploited, calling for an effort in analysis and modeling. Our understanding of the impact of the temporal dimension of networked structures on the behavior of dynamical processes running on top of them can be applied to more complex multi-layered systems, with particular attention to the effect of temporal correlation between the layers in the diffusion dynamics.
La revolució de dades en ciències socials ha revelat els complexos patrons de les interaccions en la dinàmica humana, com ara l'heterogeneïtat i la burstiness dels contactes socials. La dimensió temporal recentment descoberta en les interaccions socials demana un esforç renovat en l'anàlisi i la modelització de xarxes empíriques de variables en el temps. Aquesta tesi contribueix a aquest programa, a través d'un doble recorregut: la modelització dels sistemes socials dinàmics i l'estudi de l'impacte de substrats temporalment variables en els processos dinàmics que es desenvolupen sobre ells. En primer lloc, hem introduït els conceptes bàsics i definicions del formalisme de les xarxes de variables en el temps, i presentem i analitzem algunes dades empíriques de les interaccions humanes de proximitat, discutint les seves principals propietats estadístiques. El cos principal de l'exposició es divideix llavors en dues parts. A la primera part ens centrem en els models de dinàmica social, amb un doble objectiu: la reproducció de les propietats de dades empíriques i el tractament analític dels models considerats. Hem presentat i discutit el comportament d'un model simple capaç de replicar les principals propietats estadístiques de les interaccions empíriques cara a cara, a diferents nivells d'agregació: individuals, grupals i d'escala col·lectiva. El model considera els individus que participen en un context social com si realitzaran una caminada a l'atzar en l'espai, i es basa en el concepte de "atractivitat social": persones socialment atractives tenen més probabilitat de que la gent que els envolta interactuï amb ells. Ens hem ocupat també de l'estudi analític del model "activity driven", destinat a capturar la relació entre la dinàmica de les xarxes variables en el temps i les propietats de les seves corresponents xarxes socials agregats. A través d'un mapeig amb el formalisme de variables ocultes, hem obtingut expressions analítiques per a les propietats topològiques de les xarxes integrades en el temps i les propietats de connectivitat de la xarxa en evolució, en funció del temps d'integració i de la forma del potencial d'activitat. A la segona part de la tesi hem estudiat el comportament dels processos difusius sobre xarxes temporals constituïdes per les dades empíriques de interaccions humanes. Primer considerem el procés de "random walk", o camí aleatori, i gràcies a les diferents estratègies de randomització que hem introduït, podem destacar el paper crucial de la correlacions temporals en alentir l'exploració del camí aleatori. Després hem dirigit la nostra atenció a la difusió d'epidèmies, centrant-nos en el cas d'un simple model SI que es desenvolupa a les xarxes temporals, complementat amb l'estudi de l'impacte de diferents estratègies d'immunització sobre la difusió de la infecció. Abordem, en particular, l'efecte de la longitud de la finestra temporal utilitzada per reunir informació per tal de dissenyar l'estratègia d'immunització, sobre l'eficàcia de la mateixa vacunació, descobrint que una quantitat limitada d'informació és suficient per maximitzar l'efecte del protocol de vacunació. El nostre treball obre interessants perspectives per a futures investigacions, en particular pel que fa a la possibilitat d'ampliar el formalisme de xarxes de temps variable a sistemes múltiplex, compostos de diverses capes de xarxes interrelacionades, en la qual els mateixos individus interactuen entre ells en diferents capes. L'anàlisi empírica de les xarxes múltiplex és encara en la seva infantesa, de fet, mentre que la mineria de dades de grans sistemes socials, de diverses capes, és madur per ser explotat, demanant un esforç en l'anàlisi i modelització. La nostra comprensió de l'impacte de la dimensió temporal de les xarxes sobre els processos dinàmics que es desenvolupen sobre ells es pot aplicar a sistemes més complexos de múltiples capes, estudiant l'efecte de la correlació temporal entre les capes en la dinàmica de difusió.

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1987.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.
Includes bibliographical references (p. 71).
This thesis is an exploration on generative collective order as establishing a physical built framework for individual identity. The emphasis on the collective stems from the premise that while incremental building may be integrative at the level of the dwelling, it may not be so at the urban level. This study proposes an alternative approach to the meeting of the scales in which the relative values and freedoms at th e various levels can be maintained under conditions of transformation. A series of observations and analysis of the vernacular settlement La Pastora are done to understand the principles present at several scales in a context where variety follows rules that are legible and reproducible. The site is analyzed with respect to its immediate context. The context is representative of three systems based on approaches to building at the urban and dwelling levels. The design for the site develops a built framework that maintains the transferable principles present in the context generating variations and aggregations that are associative to individual identity.
by Josefina Garcia Marquez.
M.Arch.

This research views the problem of delayed motherhood as a complexity of time: firstly, within the life trajectory of the child/adolescent/young woman/mid-life adult, and secondly, in relation to inherited factors that came before her entry into this life, threatening to continue after it. The thesis argues, from an advocacy perspective, for a period of mid-life that we could call a Pregnant Pause, which, as the research demonstrates, points to an early rupture in nurturing and relating. The research follows 8 women who have become pregnant in mid life. Using interviews, dream diaries and the Word Association Test, the thesis identifies those factors within personal, cultural and collective complexes influencing onset of late procreative desire. These are discussed in relation to causation and teleological continua. The empirical work yielded data rich in presentations of difficulties with the maternal parent, while the paternal parent remained marginalized. In parallel, the presence of a male sibling was found to have a significant effect on how women unconsciously organized their lives into two parts, “first Adam, then Eve”, insofar as identities around work and the maternal were concerned. The thesis concludes with a discussion of the interconnection between the individuating woman and the culture in which she is born, arguing that delayed motherhood is both an act of rebellion and redemption. Identification of a Pregnant Pause within these life trajectories clarifies three phases of delayed motherhood: before a baby, desperate for a baby, and after the baby. The implications of this research are discussed in parallel as dissociation from trauma, facing into earlier trauma with renewed determination, and transformations inspired by the Trickster archetype. The implications of this research range from, how not to raise a daughter, through to raising awareness on how the mother-daughter relationship impacts delayed motherhood and thus society, ultimately to address the need to re-imagine a national health service that values the personal and social impact on women who have lived their lives in two parts. This research aims to serve women who have no other means of redeeming their lost years except to find support for a reproductive identity through the NHS.

We have all witnessed the flocking of starlings in the sky and the schools of fish that form in the ocean. This kind of organization of living creatures is not limited to those that we see, but also occurs for those that we don’t : swimming microorganisms. Suspen- sions of micro-swimmers exhibit a rich dynamics. Their behaviors can play an important role in the survival of the group, its development, the balance between species, their trophic strategies and even animal fertility. They can form coherent structures due to collective motion, mix the surrounding fluid or modify its rheological properties. Such diversity results from the complex interplay between swimming strategies, physiological processes, chemical reactions and hydrodynamic interactions. Fluid Mechanics is there- fore essential to understand and master the mechanisms involved in these phenomena. While experimental studies bring out new findings and, sometimes, provide physical ex- planations, modeling remains essential. Yet, including an accurate description of the micro-swimmers in a suspension containing thousands (nay millions) individuals, requires considering a wide range of coupled scales (from one micron 10^−6m to several millimeters 10^−3m). What happens on large scales depends on sophisticated mechanisms occurring two or three orders of magnitude below. Therefore, the multiscale modeling of such phenomena is still a major challenge for the state-of-the-art numerical methods. This thesis aims at providing a contribution in that direction. In a first part, we will show that reproducing swimming mechanisms at the scale of the micro-swimmer can be achieved with various models spanning different levels of complexity. We will then present our developments to incorporate these models in an efficient framework for large scale simulations. We will show how to simultaneously account for the Brownian motion of the smallest particles (10^−6m). Our code reproduces known results from the literature with the same accuracy, but at lower cost and at larger scales, thus bridging a gap between particle-based models, experiments and continuum formulations from kinetic theory. Using the capabilities afforded by our method, we eventually address two open problems in the experimental literature : the origins of orientational correla- tions between interacting self-propelled micro-droplets and the mechanisms at play in the nonlinear enhancement of Brownian particle diffusion in active suspensions.

This thesis argues for the fundamental importance of the opposition between holistic and reductionistic world-views in economics. Both reductionism and holism may nevertheless underpin laissez-faire policy prescriptions. Scrutiny of the nature of the articulation between micro and macro levels in the writings of economists suggests that invisible hand theories play a key role in reconciling reductionist policy prescriptions with a holistic world. An examination of the prisoners' dilemma in game theory and Arrow's impossibility theorem in social choice theory sets the scene. The prisoners' dilemma epitomises the collective irrationality coordination problems lead to. The source of the dilemma is identified as the combination of interdependence in content and independence in form of the decision making process. Arrovian impossibility has been perceived as challenging traditional views of the relationship between micro and macro levels in economics. Conservative arguments against the possibility in principle of a social welfare function are criticised here as depending on an illicit dualism. The thesis then reviews the standpoints of Smith, Hayek and Keynes. For Smith, the social desirability of individual self-seeking activity is ensured by the 'invisible hand' of a god who has moulded us so to behave, that the quantity of happiness in the world is always maximised. Hayek seeks to re-establish the invisible hand in a secular age, replacing the agency of a deity with an evolutionary mechanism. Hayek's evolutionary theory, criticised here as being based on the exploded notion of group selection, cannot underpin the desirability of spontaneous outcomes. I conclude by arguing that Keynes shares the holistic approach of Smith and Hayek, but without their reliance on invisible hand mechanisms. If spontaneous processes cannot be relied upon to generate desirable social outcomes then we have to take responsibility for achieving this ourselves by establishing the appropriate institutional framework to eliminate macroeconomic prisoners' dilemmas.

The purpose of the current analysis is to look at both individual and contextual predictors of perceived risk of victimization. Specifically, the present work builds directly on the contributions of Rountree and Land (1996) and goes beyond their work in several ways. The current work includes additional census tract measures and redefines a key concept index. Drawing upon routine activity theory, social disorganization theory, and social disorder theory, the current analysis includes individual, neighborhood, and census tract level predictors of perceived risk. Data collected on neighborhood characteristics and crime rates in Seattle, Washington in 1990 are used. Using a multi-stage sampling design, 5,302 individuals were surveyed. Multinomial logistic regression is used in this analysis. General support is found for routine activity theory, social disorganization theory, and social disorder theory. Most notable, however, support is found for including census tract level measures. Suggestions for future research are discussed.

This research has shown how the nature of the construction project has become increasingly complex and has highlighted how project management decision-making has been supplemented with the use of risk management strategies. Subsequently the use of risk management strategies in construction project execution has had some of its weaknesses exposed, namely the failure of such strategies to consider the role of the individual within the risk management process. Consequently this research has undertaken an investigation to ascertain and understand the nature and impact of individual decision-makers upon the decision-making process. The attributes of and influences upon individual decision-making, risk and uncertainty perceptions and preferences have been explored and discussed in some detail. From those the `risk prism', a metaphor for the perception and preference of risk and uncertainty, was developed to explore the manner in which these decision-making attributes function. An investigation was undertaken to replicate the `risky shift' phenomenon in decisionmaking groups populated by construction project management professionals. The results of this investigation ascertained the influence of the group environment upon construction management decision makers, namely that individuals were influenced to accept greater uncertainty in a group decision environment. Subsequently a case study investigation of an organisations attempt to introduce a new risk management strategy was undertaken from which an enhanced understanding of the group discussion and decision-making environment was ascertained. As a result of these investigations an improved risk management process was developed and is presented within this dissertation.

This thesis examines empirical and theoretical issues related to the role of uninsurable individual risk and heterogeneity in macroeconomics. The thesis includes four chapters. The first chapter uses data from the Panel Study of Income Dynamics (PSID) to test full risk-sharing among North American households. The second chapter is a short essay where I use simulated data to show how the method applied in the previous chapter can be used to distinguish between partial risk sharing and imperfect credit markets. The third chapter develops a heterogeneous agent dynamic general equilibrium model which jointly models aggregate saving and employment. Finally, the fourth chapter investigates empirically the ability of financial market incompleteness to help explaining the equity premium puzzle. The central motivation throughout this dissertation is the recognition that the interaction between cross-sectional volatility and aggregate volatility is of fundamental importance to understand the way we should model macroeconomic aggregates such as aggregate consumption, asset prices and business cycle fluctuations.

Doctorat en Sciences économiques et de gestion
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A distribuição dos recursos nos domicílios é importante para a compreensão do bem-estar material de seus integrantes e para a formulação de políticas redistributivas. Apesar da aparente importância da dimensão intrafamiliar da desigualdade, muito pouco tem sido feito para entender o quanto dos recursos do domicílio são apropriados pelos indivíduos que o compõem, e assim, tentar avaliar a pobreza individual. De fato, a avaliação da pobreza e da desigualdade, muitas vezes, assume uma distribuição igualitária dos recursos entre os membros do agregado familiar. Além disso, as medidas de pobreza não apenas negligenciam a distribuição dos recursos dentro dos domicílios, mas também os ganhos decorrentes do consumo conjunto. No entanto, a parcela de recursos domésticos dedicados a cada membro da família é difícil de identificar porque o consumo é medido ao nível do domicílio e os bens podem certamente ser compartilhados. Esta pesquisa tentou analisar o grau de desigualdade dentro das famílias e sua contribuição para os níveis de pobreza no contexto brasileiro. Em particular, estimou-se o processo de alocação de recursos e as economias de escala nos domicílios do Brasil usando um modelo coletivo de consumo das famílias. Mais especificamente, tentou-se analisar as parcelas de recursos de crianças e adultos e a relação com as economias de escala decorrentes do consumo conjunto e o processo de barganha dos pais, a fim de calcular uma medida direta da pobreza individual para o Brasil. A identificação da parcela de recursos dos membros do agregado familiar requer, além da observação de bens específicos dos adultos, a estimativa conjunta de curvas de Engel para domicílios de casais e solteiros. Esta estratégia de identificação difere do método tradicional de Rothbarth na medida em que é compatível com as economias de escala, bem como com o processo de barganha parental. A base de dados utilizada foi a Pesquisa de Orçamentos Familiares do Brasil (POF 2008-2009). Os principais resultados forneceram evidência de desigualdade e economias de escala dentro dos domicílios brasileiros, o que nos leva à rejeição do modelo unitário de consumo e da abordagem tradicional de Rothbarth no caso do Brasil, respectivamente. Os resultados também mostraram que a parcela dos gastos totais dos homens é ligeiramente maior do que as parcelas das mulheres para quase todas as estruturas familiares consideradas no presente trabalho. Por sua vez, a magnitude das parcelas das crianças, interpretadas como o custo dos filhos para os pais, é comparativamente menor. Outros resultados também mostraram como os recursos destinados a cada membro variam de acordo com o tamanho e a estrutura da família, e, em particular, como as medidas tradicionais de pobreza tendem a superestimar a incidência da pobreza infantil. Além disso, encontrou-se que a parcela de recursos dedicada às crianças aumenta com o número de crianças, mas a parcela média por cada criança tende a diminuir. Por outro lado, verificou-se que as economias de escala dos adultos são grandes e afetam as medidas de pobreza. Especificamente, a pobreza entre adultos é menor porque os pais são altamente compensados pelas economias de escala decorrentes do consumo conjunto. Apesar de os filhos comandarem uma parcela de recursos razoavelmente grande do agregado familiar, tal parcela não é suficiente para evitar que eles tenham taxas mais elevadas de pobreza do que os seus pais. Além disso, foi encontrado que as mães parecem contribuir com mais recursos para os filhos do que os pais, e por outro lado, não foram encontradas diferenças de gênero, mas sim diferenças etárias nas parcelas de recursos entre as crianças. Ainda, os resultados fornecem evidências indicando que o poder de barganha das mulheres dentro da família melhora com a idade, nível de educação e a participação no mercado de trabalho. No geral, a principal conclusão é que a desigualdade intrafamiliar é significativa. Uma consequência importante disso é que as medidas tradicionais per capita de pobreza, que, por construção, ignoram a desigualdade intrafamiliar, apresentam uma imagem enganosa da pobreza, em especial para as crianças. Finalmente, essas estimativas são importantes para as intervenções de políticas redistributivas, porque constituem medidas mais precisas do bem-estar material relativo dos brasileiros em domicílios de diversas composições. Igualmente, o fato de que é plausível medir as parcelas de recursos de cada membro das famílias é um passo muito útil para medir a pobreza individual e, assim, informar de forma mais precisa aos formuladores de políticas que estão focados na redução da pobreza.
The distribution of resources within households is crucial to the understanding of its members’ material well-being and for the design of redistributive policies. Although the apparent importance of the intra-household dimension of inequality, very little research has focused on how much of the family resources are dedicated to each member, and thereby attempting to assess individual poverty. In fact, the assessment of poverty and inequality often assumes an equal distribution of resources among household members. Moreover, poverty measures not only neglect the distribution of resources within families, but also the gains from joint consumption. However, the share of household resources devoted to each family member is hard to identify, because consumption is measured at the household level and goods can indeed be shared. This research attempted to analyze the extent of inequality within households and its contribution to levels of poverty in the Brazilian context. In particular, we estimated the process of resources allocation and economies of scale in households from Brazil using a collective model of household consumption. More specifically, we attempted to analyze the resource shares of children and adults in relation with the scale economies of joint consumption and the parental bargaining in order to calculate a direct measure of individual poverty for Brazil. The identification of the household member’s resource share requires the observation of adult-specific goods and a joint estimation on couples and singles. This identification strategy differs from the traditional Rothbarth method, in that it is compatible with economies of scale as well as with parents’ bargaining. The database used was Pesquisa de Orçamentos Familiares (POF 2008-2009). The main results provide evidence of inequality and economies of scale within Brazilian households, which leads us to the rejection of the unitary model and the traditional Rothbarth approach for Brazil, respectively. Our findings also showed that men’s share of total expenditures is slightly larger than women's shares for almost all the family structures considered here. The magnitude of children’s shares, interpreted as the cost of children for the parents, is in turn comparatively smaller. We also showed how resources devoted to each household member vary by family size and structure, and we find that, particularly, standard poverty measures tend to overstate the incidence of child poverty. Furthermore, we found that the share of resources devoted to children rises with the number of children, but the average share per child tends to decrease. On the other hand, we found that adult's scale economies are large and affect poverty measures. Specifically, adult poverty is smaller because parents are highly compensated by the scale economies due to joint consumption. Despite that the children command a reasonably large share of household resources, such share is not enough to avoid having higher rates of poverty than their parents. In addition, we found that mothers seem to contribute more resources than fathers to children, and we do not find evidence of gender but age differences in children’s resource shares. Also, results provide evidence indicating that women’s bargaining power within the household improves with their age, level of education and participation in the labor market. Overall, our main finding is that there is substantial intra-household inequality. One important consequence of this is that standard per-capita poverty measures, which by construction ignore intra-household inequality, present a misleading picture of poverty, particularly for children. Finally, our estimates are important for redistributive policy interventions, because they constitute more accurate measures of the relative material welfare of Brazilians in households of varying composition. Furthermore, the fact that it is plausible to measure of each member’s resource shares within households is a very useful step in measuring individual poverty, and thus informing in a more precise way to policy makers which are focused on poverty alleviation.
Sem Lattes

While the field of educational research has produced an enormous amount of literature relevant for improving teaching and, ultimately, student achievement, the field has been less successful at producing deep and lasting instructional change at scale. In this dissertation, I present three papers that explore an approach to program implementation that attempts to cultivate conditions to support scale by involving teachers in a process of collaborative inquiry around an evidence-based program called READS for Summer Learning (READS). While many have called for implementation approaches that give educators an opportunity to make adaptations, few studies have examined the ways in which teachers respond to such an approach, including: the process that teachers go through as they are making their adaptation decisions, the kinds of adaptations they make, and the ways in which participation in such an approach may affect their perceptions of the program. In this thesis, I begin to address these gaps. Together, the papers in this dissertation explore how teachers at three high-poverty schools in one urban district responded when given opportunities—both as individuals and as teams—to make structured adaptations to READS. In the first study, I focus on individual teachers’ enactments of READS in their classrooms. The purpose of this study was to explore individual teachers’ fidelity to and adaptations of the core component of READS in which teachers have the most responsibility—teaching the READS lessons. In the second study, I consider the adaptation decisions that grade-level teams arrived at through a collaborative inquiry process. In my third study, I use interview data, collected after the implementation of the school-based components of READS (including the lessons) but before the end of the summer, to explore teachers’ expectations of the program’s effectiveness for their students and the basis for these expectations. Taken together, these studies provide insight into what success might look like when it comes to giving teachers greater autonomy over the implementation of evidence-based programs, as well as how researchers and school leaders might support these kinds of efforts.

Social behaviour is shaped by complex relationships between evolutionary and ecological processes interacting at different scales. Benefits gained from social associations can range from predator dilution to collective sensing, but little is known about how these can be influenced by social structure and phenotypic composition. In this thesis, I investigated how individual decision-making affects phenotypic social structure, and how this mediates social behaviour through emergent properties of collective group behaviour. First, using mixed-species flocks as a model system, I showed individual tits (Paridae, chapter 2) and thornbills (Acanthizae, chapter 3) varied significantly in their social positions. Within-species variation in network position was as large as between-species variation, sug- gesting that prescribing functional roles at the species level may not sufficiently account for potential differences in fitness operating at the individual level. Rather, this suggested that structure may be driven by phenotypic traits, underpinning network structure (chapter 4). Next, I used an extensive data set of foraging records to explore factors determining the composition, of flocks of great tits (Parus major, chapter 5). For example, assortment by dispersal phenotype (immigration status) was the result of spatial disaggregation, and I showed that this may facilitate social selection for breeding territories (chapter 6). Finally, I investigated how decision-making shaped mixed-species social structure. I found that tits used a common strategy for managing pressures of predation and starvation by shifting from exploration to exploitation at different times of the day (chapter 7). I then found that a very simple interaction rule successfully replicated mixed-species group structure (chapter 8). Strikingly, the same rule was applied to both conspecifics and het- erospecifics, potentially playing an important role in the maintenance of flock structure. Through experimental manipulation of ecological conditions, I found that heightened per- ceived predation resulted in stronger social attraction overall, whereas increased competition led to a reduction in attraction to conspecifics (chapter 9). Simulations suggested this could be one potential mechanism underpinning fission-fusion dynamics in these species. Together, the results in this thesis form a framework linking social behaviour to individ- ual fitness where natural selection is shaped by the social environment. This approach may prove useful for testing whether following common social rules reduces variance in benefits accrued by individuals, and how within-species variation in social behaviour can impact emergent properties of groups.

Navigating the physical world may present only a small fraction of the challenges faced by social animals. Sociality brings with it numerous benefits, including access to important information that may have otherwise been harder to come by. However, almost every aspect of these apparent benefits may also entail additional cognitive challenges, including how to interpret signals from conspecifics, who to attend to, and how to incorporate knowledge about signallers when deciding how to respond. One approach to understanding the cognitive abilities associated with social function is to investigate social species that take part in potentially costly group behaviours, where individual decisions must be made in a social context. In this thesis I explore how jackdaws (Corvus monedula), a highly sociable corvid species, use acoustic information to coordinate collective anti-predator responses. In Chapter Two I showed using playback experiments that the magnitude of collective responses to anti-predator recruitment calls known as “scolding” calls depends on the identity of the caller, with larger responses to familiar colony members than unfamiliar individuals. In Chapter Three I then used habituation-dishabituation experiments to show that this vocal discrimination operates at the level of the individual, with jackdaws discriminating between the calls of different conspecifics, regardless of their level of familiarity. In Chapter Four, I examined whether aspects of call structure conveyed information about threat levels. Here, I found that high rates of scolding calls were associated with elevated threats, and playback experiments suggested that this information might result in larger group responses. The finding that jackdaws are capable of mediating their response to alarm calls based on the identity of the individual caller, and on structural variation in call production, raised the question of whether jackdaws employed similar forms discrimination between acoustic cues made by predators in their environment. I investigated this in Chapter Five, using playback experiments to show that jackdaws responded not only to the vocalisations of resident predators, but that this ability extended to novel predators, and that responsiveness was mediated by the phase of the breeding season in which predators were heard. Together, these findings provide insights in to how discrimination among acoustic cues can mediate group behaviour in species that respond collectively to threats.

The present study aims to contribute to insurance sector by investigating the risk reduction mechanisms: self-insurance, self-protection, and market insurance. First, individual valuations/demands for these mechanisms in fire and earthquake events are analyzed through conducting an experiment to 78 students from Middle East Technical University In addition, the effects of risk attitude, personality traits, and demographic variables (that are measured through using a questionnaire) on valuations to these precautionary actions&rsquo
are examined. The findings show that, consistent with the theory, self-insurance and market insurance are substitutes to each other
contrary to the theory, self-protection and market insurance are not complements, they are also substitutes to each other. Further, individuals prefer self-protection and self-insurance to market insurance for both fire and earthquake events. Lastly, individual investment attitude is found to affect the valuations of these three risk reduction mechanisms positively concluding that people perceive these mechanisms as an investment tool.