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Presents a critical overview of the literature on early warning systems and leading indicators of crisis. Examines the signalling method, the discrete choice approach, and structural models. Concludes with a critical evaluation of the econometric methodology used in this literature and an assessment of the empirical literature on contagion.

This chapter discusses various assumptions underlying the common factor model and the procedures typically used in its implementation. Ideally, these assumptions should be carefully considered by researchers prior to collecting any data for which an exploratory factor analysis is likely to be used. The chapter first considers the key assumptions underlying the common factor model itself, with particular reference to assumptions about how common factors influence measured variables. It compares effects indicator models and causal indicator models as well as linear effects versus nonlinear effects of common factors. It then explores assumptions underlying various procedures commonly used to fit the common factor model to data. It also explains the nature of each assumption and when it is or is not likely to be plausible, along with methods for evaluating the plausibility of the assumption. Finally, it outlines various courses of action when a given assumption is not met.

When Charles Darwin wrote On the Origin of Species (1859), he issued a challenge to potential critics: “If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not be produced through natural selection”. Darwin went even further by identifying several traits that seemed especially problematical: the sterile worker castes of social insects and extravagant ornaments that appear to benefit potential predators more than their bearers. It is this latter problem and Darwin’s solution to it—sexual selection—that are the focus of this chapter. I begin by providing a very brief historical overview of sexual selection, focusing on the initial controversies and its resurgence in the 1970s. I then provide an overview of the conditions that lead to sexual selection and the kinds of traits that are favored by it. Sexual selection usually involves evolutionary changes in both males and females. Thus, I first address the evolution of extravagant male traits (it is typically males that exhibit such traits). Since female choice is one of the mechanisms that can lead to the evolution of extravagant male traits, I also address the evolution of female preferences. Finally, I will identify those areas of the field that are the most controversial, unresolved, and promising for future research. This review is, of necessity, brief and selective. I have tried to cite recent reviews rather than the extensive primary literature to provide an easy entry point into the literature. Readers wishing for more detailed treatment would do well by starting with Andersson’s (1994) excellent book. Darwin introduced the concept of sexual selection in On the Origin of Species (1859) and greatly elaborated the idea in The Descent of Man and Selection in Relation to Sex (1871). Darwin defined sexual selection as depending “not on a struggle for existence, but on a struggle between males for possession of the females”.

Policy connects law to the social and political world. Research in policy matter—making, implementing, and evaluating—can be better done not by the mono-linear approach of allowing the discourse to revolve only around a rough idea; but by surveying all the policy alternatives, examining them from different angles with reference to certain paramount goals such as welfare, social justice, and human rights, and arriving at some sustainable inference. As policy research being conducted by new players such as NGOs, institutions, and stakeholders, in addition to state and inter-disciplinary characters of policy research has come to stay, proper designing of policy research becomes imperative. Tools of policy research include participatory assessment, which involves conducting of collective assessment; imagination of future scenarios; appropriate indicators; models of change; and cost benefit analysis. Empirical research for policy making or evaluation is also valuable. Policy research has made substantive contributions and has great potentiality.

At each new generation, sexual reproduction creates new combinations of nuclear and mitochondrial genes, and the potential arises for mitonuclear incompatibilities and reduced fitness. Sexual selection plays a key role in maintaining mitonuclear coadaptation across generations because it enables pre-zygotic sorting for coadapted mitonuclear genotypes. In this chapter, I present data that individuals engaged in mate choice select partners with correct species-typical mitochondrial and nuclear genotypes as well as individuals with highly functional cellular respiration. The implication is that mate choice for compatible nuclear and mitochondrial genes can play a significant role in generating the patterns of ornamentation and preferences observed in animals.