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Models with multiple equations rather than a single equation are the subject of Chapter 4. It covers model specification, implied moments, model identification, model estimation, and model interpretation, fit, and diagnostics in the context of such models. The consequences of measurement error and the treatment of mediation effects are part of the chapter. Finally, the chapter compares simultaneous equation models and Directed Acyclic Graphs (DAGs).
Chapter 3 concentrates on single equation regression models but presents them from the perspective of structural equations models. It introduces and applies the major steps of structural equation modeling: model specification, implied moments, model identification, model estimation, and model interpretation and fit. It also includes diagnostics and testing for regression and a discussion of the consequences of using multiple regression with variables measured with errors.
Many political science theories posit empirical relationships that are conditioned by some moderating variable, which scholars model using a multiplicative interaction term in a regression. In recent years, scholars have begun using such terms in dynamic regression models with time series data. However, the lack of guidance on adding multiplicative interactions to these workhorse models exposes problems with the consistency of the estimator, model restrictions, and interpretation. This paper provides theoretical and practical guidance to address these problems. First, we define the conditions under which scholars can ensure consistent estimates when estimating relationships conditioned by a moderating variable in dynamic models. Second, we introduce a general model that makes no theoretical assumptions about precisely how conditional relationships unfold over time. Third, we develop a flexible approach for interpreting such models. We demonstrate the advantages of this framework with simulation evidence and an empirical application.
The successful establishment of the bacterial community in the gastrointestinal tract is of crucial importance for growth, metabolic health, performance and welfare in early and later stages of ruminants. This study aimed to investigate the development of oral- and rumen-associated bacteria in pre-weaning calves and to compare them with respect to the different genetic backgrounds and the type of $\beta $-casein in the milk fed. Calves were kept in the same defined nutritional and housing environment. Saliva samples were taken at three time points up to 27 days of age before weaning via buccal swabs, and the extracted DNA was analysed using 16S rRNA gene amplicon sequencing. The development of the microbiota in the rumen and oral cavity was differentially analysed and evaluated. Age-dependent changes were observed, with a clear shift in rumen-associated bacteria over time and increasing alpha diversity, while oral-associated bacteria stabilized more rapidly at a young age, demonstrating the robustness of the analysis. Breed-specific differences were noted at the genus level, and minor effects of milk type (based on β-casein type) were detected. A significant interaction was detected between calf age and bacterial abundance, as well as between the breed and bacterial abundance, but not for milk type. The method for analysing and evaluating saliva samples provided valuable insights into the development of the microbiota in the oral cavity and the rumen under the influence of breed and the milk fed by the successful separation of oral- and rumen-associated bacteria. Due to the exclusive use of samples from the oral cavity, invasive examination methods could be largely avoided in the future and would only serve as additional controls to confirm the results of the buccal swab analyses.
The paper investigates processes and consequences of ‘philanthropic kinning’, that is the use of kinship and family idioms in constructing and maintaining personal relations between donors and recipients in philanthropy. Usual studies collapse the occurrence of kinship metaphors in philanthropy either as evidence of ‘prosociality’ (e.g. trust, care or love) or more frequently as evidence of ‘paternalism’ (power and domination of donors over recipients, and their objectification). This paper claims that introducing kinship and parenting studies into researching philanthropy would greatly refine our understanding of donor–recipient relations. In the framework of a qualitative case study of a philanthropic ‘godparenthood’ programme organised in Hungary supporting ethnic Hungarian communities in Romania, this paper looks at the roles, responsibilities and obligations various forms of philanthropic kinship offer for the participants; and relations of power unfolding in helping interactions. With such concerns, this paper complements earlier research on hybridisation of philanthropy, through its sectoral entanglements with kinship and family. Also, it contributes to research on inequalities in philanthropy, by showing how philanthropic kinning may recreate, modify or reshape donor–recipient power relations in diverse ways.
To understand a treatment’s potential impact at the individual level, it is crucial to explore whether the effect differs across patient subgroups and covariate values. Meta-analysis provides an important tool for detecting treatment–covariate interactions, as it can improve power compared to a single study. However, aggregation bias can occur when estimating individual-level treatment–covariate interactions in meta-analysis, due to trial-level confounding. This refers to when the association between the covariate and treatment effect across trials (at the aggregate level) differs from that observed within trials (at the individual level). It is, thus, recommended that heterogeneity in the treatment effect at the individual level should be disentangled from that at the trial level, ideally using an individual participant data (IPD) meta-analysis. Here, we explain this issue and provide new intuition about how trial-level confounding is impacted by differences in within-trial distributions of covariates and how this corresponds to asymmetry in subgroup-specific funnel plots in the case of categorical covariates. We then propose a sensitivity analysis to assess the robustness of interaction estimates to potential trial-level confounding. We illustrate these concepts using simulated and real data from an IPD meta-analysis of trials conducted on the TICO/ACTIV-3 platform, which assessed passive immunotherapy treatments for inpatients with COVID-19.
Multivariable analysis is needed because most events, whether medical, politica, social, or personal, have multiple causes. And these causes are related to one another. Multivariable analysis enables us to determine the relative contributions of different causes to a single event or outcome.
Multivariable analysis enables us to identify and adjust for confounders. Confounders are associated with the risk factor and causally related to the outcome. Adjustment for confounders is key to distinguishing important etiologic risk factors from variables that only appear to be associated with outcomes due to their association with the true risk factor.
Stratification can also be used for identifying independent relationships between risk factors and outcomes but becomes too cumbersome when there are more than one or two possible confounders.
This comparative article examines the iterative interactions between the French conception of guerre contre-révolutionnaire and the (re-)legitimation of modern torture techniques from the late nineteenth to the early twenty-first centuries. Based on a threefold argument, and drawing on multilingual historical sources and museal artifacts, it argues that the ideological campaign against the “revolutionary war” was a specifically military-intellectual approach to dealing with real or imagined subversive enemies. This dispositif promoted torture as a method of obtaining information and intimidating victims. First, this article shows how torture and the corresponding knowledge production can be traced back to colonial Indochina. There, archaic techniques were peculiarly blended, often with other experiences and indigenous practices. Later, leading military officers believed that the resulting doctrine of counterrevolutionary warfare was successful largely because of the use of methods of torture that left no trace. This key feature facilitated the export of its techniques to other regions. Therefore, in a second step, this article shows how this intertwined knowledge system was applied to the Algerian War, where it was widely employed and exploited. Subsequently, the fear of the spread of global communism facilitated the emergence of torture as a covert science of the Cold War. Third, this essay demonstrates how leading French theorists globalized their teachings by influencing their South American counterparts through their cross-continental interactions from the 1960s onward. Since the end of the Cold War, traces of this savoir-faire have remained potent, culminating in their influence on U.S. American counterinsurgency doctrine.
Until now, we’ve only considered the motion of a single particle. If our goal is to understand everything in the universe, that’s a little limiting. In this section, we take a small step forwards: we will describe the dynamics of multiple interacting particles. Among other things, this will highlight the importance of the conservation of momentum and angular momentum.
In the study approaches we have looked at, the main purpose of investigation has been to understand and quantify relationships – relationships between exposures and outcomes, or between interventions and effects. And, just like the common plot line of a romantic tale, in this chapter we will consider how we can work out if those relationships are the ‘real deal’. How do we know we have measured what we think we have (is this really love?) and how much of the effect we have measured is entirely due to the exposure or intervention (or just a holiday thing)?
This paper explores the evolution of the concept of peace in the context of a globalized and digitalized 21st century, proposing a novel vision that shifts from viewing peace as a thing or a condition, to understanding peace as dynamic and relational process that emerges through human interactions. Building on - yet also going beyond - traditional definitions of peace as something to be found through inner reflection (virtue ethics), as the product of reason, contracts and institutions (Enlightenment philosophy), and as the absence of different forms of violence (modern peace research), this paper introduces a new meso-level theory on networks, emphasizing the importance of connections, interactions and relationships in the physical and online worlds. The paper is structured around three main objectives: conceptualizing relational peace in terms of the quantity and quality of interactions, mapping these interactions into networks of peace, and examining how these networks interact with their environment, including the influence of digital transformation and artificial intelligence. By integrating insights from ethical and peace research literature, the paper makes theoretical, conceptual, and methodological contributions towards understanding peace as an emergent property of human behavior. Through this innovative approach, the paper aims to provide clarity on how peace (and violence) emerges through interactions and relations in an increasingly networked and digitalized global society, offering a foundation for future empirical research and concerted policy action in this area. It highlights the need for bridging normative and descriptive sciences to better understand and promote peace in the digital age.
Conditioning on variables affected by treatment can induce post-treatment bias when estimating causal effects. Although this suggests that researchers should measure potential moderators before administering the treatment in an experiment, doing so may also bias causal effect estimation if the covariate measurement primes respondents to react differently to the treatment. This paper formally analyzes this trade-off between post-treatment and priming biases in three experimental designs that vary when moderators are measured: pre-treatment, post-treatment, or a randomized choice between the two. We derive nonparametric bounds for interactions between the treatment and the moderator under each design and show how to use substantive assumptions to narrow these bounds. These bounds allow researchers to assess the sensitivity of their empirical findings to priming and post-treatment bias. We then apply the proposed methodology to a survey experiment on electoral messaging.
Early education and care (ECEC) is part of the everyday life of most children in developed economies, presenting exceptional opportunity to support nutrition and ongoing food preferences. Yet, the degree to which such opportunity is captured in policy-driven assessment and quality ratings of ECEC services is unknown.
Design:
Abductive thematic analysis was conducted, guided by key domains of knowledge in nutrition literature and examining identified themes within these domains.
Setting:
ECEC services (n 38) in Queensland, Australia.
Participants:
Data were a random sample of field notes pertaining to mealtimes and food provision (n 182) collected as evidence to inform quality ratings during assessment visits to ECEC services.
Results:
The field notes mapped to three theory-driven domains: provisions, practices and education. Reflecting policy specification, health, hygiene and safety were a key focus, but food quality and quantity were not. Assessors noted the promotion of child autonomy at mealtimes, yet little evidence pertaining to characteristics of educator-child interactions.
Conclusions:
Despite evidence that childhood nutrition is crucial for optimal development and learning, the quality and quantity of food are not directly assessed. Relationships and interactions at mealtimes provide an environment ideal for promoting learning and development, yet the policy guiding inspection and assessment of ECEC services directs focus to a more limited lens of safety, hygiene and promotion of ‘healthy foods’. Our findings identify a narrow conceptualisation of mealtimes focused on ‘health’ as limiting the potential to leverage mealtimes as places to support children’s nutrition and attendant development and learning.
Goodman's (1979, 1981, 1985) loglinear formulation for bi-way contingency tables is extended to tables with or without missing cells and is used for exploratory purposes. A similar formulation is done for three-way tables and generalizations of correspondence analysis are deduced. A generalized version of Goodman's algorithm, based on Newton's elementary unidimensional method is used to estimate the scores in all cases.
Classic item response models assume that all items with the same difficulty have the same response probability among all respondents with the same ability. These assumptions, however, may very well be violated in practice, and it is not straightforward to assess whether these assumptions are violated, because neither the abilities of respondents nor the difficulties of items are observed. An example is an educational assessment where unobserved heterogeneity is present, arising from unobserved variables such as cultural background and upbringing of students, the quality of mentorship and other forms of emotional and professional support received by students, and other unobserved variables that may affect response probabilities. To address such violations of assumptions, we introduce a novel latent space model which assumes that both items and respondents are embedded in an unobserved metric space, with the probability of a correct response decreasing as a function of the distance between the respondent’s and the item’s position in the latent space. The resulting latent space approach provides an interaction map that represents interactions of respondents and items, and helps derive insightful diagnostic information on items as well as respondents. In practice, such interaction maps enable teachers to detect students from underrepresented groups who need more support than other students. We provide empirical evidence to demonstrate the usefulness of the proposed latent space approach, along with simulation results.
Climate change has already profoundly changed the ecological world on all levels of the biological hierarchy. Comparing the past with the present allows researchers to document that changes have happened, and to understand why some groups (e. g. birds vs. mammals in the Mojave Desert) respond differently than others. Climate change has already changed population phenology, and researchers can estimate the speed of phenological change. Population range shifts may occur on two fronts: leading-edge expansion and trailing-edge contraction. Both of these processes are influenced by biotic and abiotic factors. Climate change can also influence the genetic structure and sex ratio of populations – in extreme cases leading to extinction. Changes to the timing of migration or to the emergence of plants and insects can cause phenological mismatch of exploitative or competitive interactions. Prey species are likely to benefit, while predators or herbivores may suffer from lack of food. On a larger scale, both terrestrial and aquatic ecosystems are showing the effects of climate change, even in tropical biomes where warming and drying are not as prominent as they are in more temperate or polar biomes. Though immune to drought, marine biomes are suffering from acidification and from low oxygen levels.
The best public speakers use a series of tricks to enchant an audience. They are revealed in this chapter and include: incorporating interactions to make a crowd feel part of the performance, signposting to continually refresh interest, the showbusiness of magic moments for truly memorable talks, the use of commanding body language, how to deal with nerves and preparing for the question and answer session.
Developing Together challenges systematic biases that have long plagued research with marginalized populations of children. It traces the unexamined assumptions guiding such research to definitions of subjectivity and the psyche based in Western cultural norms. The book provides alternative paradigms, applying a comprehensive methodology to two unique schooling contexts. Through this new approach children's development can be seen as an interactive, collaborative process. The chapters highlight how theoretical assumptions directly influence research methods and, in turn, affect educational practices. Unique in its provision of a detailed alternative method for conducting research with children, the book explains how the study of collaborative competence would influence education and applied fields. It is an essential resource for researchers in developmental psychology, educators, and policymakers alike.
The principle of distinction in International Humanitarian Law sets up two entities, the civilian and the combatant, and organises the relationship between them. This socio-legal chapter draws on original research from South Sudan to explore how this principle is operationalised in humanitarian–peacekeeper interactions. Humanitarian actors routinely invoke ‘distinction’ as they navigate operational dilemmas with respect to the use of military assets, and in their relationship with the UN Mission in South Sudan more generally. Two ‘ideal types’ of humanitarian actor emerge here. The first type takes a strict approach to distinction, thinking long term and eschewing military asset use that undermines distinction. The second type interprets distinction flexibly and balances it with other goals such as reaching people in need; this exposes a hidden conflict between the principles of distinction and humanity. Through these everyday interactions – which sometimes involve drawing lines within the civilian category – humanitarian actors produce distinction in law, in practice, and in perception.
Biological data commonly involve multiple predictors. This chapter starts expanding our models to include multiple categorical predictors (factors) when they are in factorial designs. These designs allow us to introduce synergistic effects – interactions. Two- and three-factor designs are used to illustrate the estimation and interpretation of interactions. Our approach is first to consider the most complex interactions and use them to decide whether it is helpful to continue examining simple interactions. Main effects – single predictors acting independently of each other – are the last to be considered. We also deal with problems caused by missing observations (unbalanced designs) and missing cells (fractional and incomplete factorials) and discuss how to estimate and interpret them.