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Scholars and policy makers need systematic assessments of the validity of the measures produced by V-Dem. In Chapter 6, we present our approach to comparative data validation – the set of steps we take to evaluate the precision, accuracy, and reliability of our measures, both in isolation and compared to extant measures of the same concepts. Our approach assesses the degree to which measures align with shared concepts (content validation), shared rules of translation (data generation assessment), and shared realities (convergent validation). Within convergent validity, we execute two convergent validity tests. First, we examine convergent validity as it is typically conceived – examining convergence between V-Dem measures and extant measures. Second, we evaluate the level of convergence across coders, considering the individual coder and country traits that predict coder convergence. Throughout the chapter, we focus on three indices included in the V-Dem data set: polyarchy, corruption, and core civil society. These three concepts collectively provide a “hard test” for the validity of our data, representing a range of existing measurement approaches, challenges, and solutions.
This chapter sets forth the conceptual scheme for the V–Dem project. We begin by discussing the concept of democracy. Next, we lay out seven principles by which this key concept may be understood – electoral, liberal, majoritarian, consensual, participatory, deliberative, and egalitarian. Each defines a “variety“ of democracy, and together they offer a fairly comprehensive accounting of the concept as used in the world today. Next, we show how this seven-part framework fits into our overall thinking about democracy, including multiple levels of disaggregation – to components, subcomponents, and indicators. The final section of the chapter discusses several important caveats and clarifications pertaining to this ambitious taxonomic exercise.
This chapter recounts how a project of this scale came together and why it has succeeded. Five main factors were responsible for V–Dem’s success: timing, inclusion, deliberation, administrative centralization, and fund–raising. First, planning for V-Dem began at a time when both social scientists and practitioners were realizing that they needed better democracy measures. This made it possible to recruit collaborators and find funding. Second, the leaders of the project were always eager to expand the team to acquire whatever expertise they lacked and share credit with everyone who contributed. Third, the project leaders practiced an intensely deliberative decision–making style to ensure that all points of view were consulted and only decisions that won wide acceptance were adopted. Fourth, centralizing the execution of the agreed–upon tasks helped tremendously by streamlining processes and promoting standardization, documentation, professionalization, and coordination of a large number of intricate steps. Finally, successful fund–raising from a mix of both research foundations and bilateral and multilateral organizations has been critical.
In this chapter we focus on the measurement of five key principles of democracy – electoral, liberal, participatory, deliberative, and egalitarian. For each principle, we discuss (1) the theoretical rationale for the selected indicators, (2) whether these indicators are correlated strongly enough to warrant being collapsed into an index, and (3) the justification of aggregation rules for moving from indicators to components and from components to higher–level indices. In each section we also (4) highlight the top– and bottom–five countries on each principle of democracy in early (1812 or 1912) and late (2012) years of our sample period, as well as the aggregate trend over the whole time period 1789–2017 (where applicable). Finally, we (5) look at how the different principles are intercorrelated in order to assess the trade–offs involved between the conceptual parsimony achieved by aggregating to a few general concepts and the retention of useful variation permitted by aggregating less.
Four characteristics of V-Dem data present distinct opportunities and challenges for explanatory analysis: (1) the large number of democracy indicators (i.e., variables), (2) the measurement of concepts by multiple coders filtered through the V-Dem measurement model, (3) the large number of years in the data set, and 4) the ex ante potential for dependence across countries (generically referred to as spatial dependence). This chapter discusses 3 challenges and 10 opportunities that are implied by these characteristics. At the end of this chapter, we also discuss three assumptions that are implicit in most analyses of observational indicators of macro-features at the national level, which aim to draw conclusions about causal relationships.
Varieties of Democracy is the essential user's guide to The Varieties of Democracy project (V-Dem), one of the most ambitious data collection efforts in comparative politics. This global research collaboration sparked a dramatic change in how we study the nature, causes, and consequences of democracy. This book is ambitious in scope: more than a reference guide, it raises standards for causal inferences in democratization research and introduces new, measurable, concepts of democracy and many political institutions. Varieties of Democracy enables anyone interested in democracy - teachers, students, journalists, activists, researchers and others - to analyze V-Dem data in new and exciting ways. This book creates opportunities for V-Dem data to be used in education, research, news analysis, advocacy, policy work, and elsewhere. V-Dem is rapidly becoming the preferred source for democracy data.
Users of V–Dem data should take care to understand how the data are generated because the data collection strategies have consequences for the validity, reliability, and proper interpretation of the values. Chapters 4 and 5 explain how we process the data after collecting the raw scores and how we aggregate the most specific indicators into more general indices. In this chapter we explain where the raw scores come from. We distinguish among the different types of data that V–Dem reports and describe the processes that produce each type and the infrastructure required to execute these processes.
V-Dem relies on country experts who code a host of ordinal variables, providing subjective ratings of latent – that is, not directly observable – regime characteristics. Sets of around five experts rate each case, and each rater works independently. Our statistical tools model patterns of disagreement between experts, who may offer divergent ratings because of differences of opinion, variation in scale conceptualization, or mistakes. These tools allow us to aggregate ratings into point estimates of latent concepts and quantify our uncertainty around these estimates. This chapter describes item response theory models that can account and adjust for differential item functioning (i.e., differences in how experts apply ordinal scales to cases) and variation in rater reliability (i.e., random error). We also discuss key challenges specific to applying item response theory to expert–coded cross-national panel data, explain how we address them, highlight potential problems with our current framework, and describe long-term plans for improving our models and estimates. Finally, we provide an overview of the end–user–accessible products of the V-Dem measurement model.
Why is the exercise of political power highly concentrated in some polities and widely dispersed in others? We argue that one important causal factor is demographic. Populous polities are characterized by less concentrated structures of authority. To explain this relationship, we invoke two mechanisms: heterogeneity and trust. The theory is demonstrated with a wide variety of empirical measures in cross-country analyses including most sovereign states and extending back to the 19th century. The result suggests the possibility of a ubiquitous ‘law’ of politics.
Los Angeles is so hot right now. Not like Paris Hilton's twittered catchphrase (although I suppose it is that too) but more in the sense of sweating through your fingernails. The TV weatherman has run out of superlatives to describe the 112 degree inferno blazing outside and has resorted to fanning himself theatrically and hooting at a crimson map of the Californian peninsula, dotted with swollen yellow suns. In an anonymous room in the Four Seasons, I'm in a puddle, even with the air-conditioning on full blast and a shelf full of condensation- dripping water bottles standing by. I'm checking the capillary creep under my armpits and wondering if there's time to dash upstairs and change my shirt when the door opens and Michael Mann scurries into the room, looking like he just stepped out of the fridge where they keep the talent chilled. He's around the table in a trice to take my soggy hand in a firm grip and carefully place a discreet Dictaphone down beside mine. In any other circumstances this would be unusual, but Mann's attention to detail is legendary and this recorded insurance is part of that cautious data-mining. Squat and intense, with swept-back hair matching his silver glasses and a confident grin, he sits himself down and motions his bored-looking assistant into a discreet chair in the furthest corner. All set, he takes a final check on everything around him, rolls his shoulders and cocks his head to one side, exposing a thin, transparent hearing aid that follows the contour of his inner ear, waiting for my first question.
I start off our conversation by casually remarking that the director has come full circle with his new film, Miami Vice. It's a kind-of remake of the seminal 1980s TV series that Mann originally brought to television screens worldwide as executive producer, the pop-culture defining success of which allowed him to write his own ticket in Hollywood, after his Hannibal Lecter story Manhunter and the Nazi horror of The Keep. He takes the observation with a nod, and shrugs his shoulders. “The time was right to make this one,” he says quickly and finally and we move on.
To report an unusual case of malignant degeneration in a ganglioneuroma of the jugular foramen post stereotactic radiosurgery as well as to systematically review the pertinent literature involving radiosurgery associated malignancies.
Ganglioneuromas are uncommon lesions of the peripheral nervous system and infrequently reported in the head and neck region. There have been no previously described cases of ganglioneuromas occurring in the jugular foramen. Malignant degeneration of these lesions is rarely described, especially in the context of radiosurgery. Radiosurgery associated malignancies overall are exceptionally rare and only a limited number of cases have been reported.
We describe a case of a ganglioneuroma occurring in the jugular foramen and mimicking the appearance of a jugular foramen schwannoma. This lesion underwent stereotactic radiosurgery and developed a delayed degeneration into a malignant nerve sheath tumor. The occurrence of ganglioneuroma in this region has not been previously described and presumed malignant degeneration is even rarer. This case highlights a previously understated risk associated with stereotactic radiation treatments. To date, 33 previous cases of stereotactic radiosurgery associated malignancies have been reported. We review the pertinent details of these cases. We caution that as follow up periods and awareness increases, reports such as this may become increasingly common.
Progressive external ophthalmoplegia (PEO) is a mitochondrial myopathy of ocular muscles. Diagnostic investigation usually involves limb skeletal muscle biopsy and molecular genetic studies, although diagnostic yield tends to be low. The purpose of this study was to evaluate the diagnostic yield obtained by analysis of levator palpebrae (LP) muscle tissue.
This is a clinicopathologic study of 8 patients with a diagnosis of PEO, who had LP muscle biopsies as part of oculoplastic procedures. Six of these patients also had limb muscle biopsies. Histopathology, electron microscopy and genetic studies were performed.
Diagnostic histopathologic findings were present in 4/6 quadriceps biopsies, and 7/8 LP biopsies. Genetic testing on DNA extracted from LP muscle revealed abnormalities in 4 patients.
In patients whose LP muscle demonstrate both genetic defects and histopathological abnormalities, the diagnosis of PEO can be confirmed without limb muscle biopsy. Patients having LP resection during oculoplastics procedures for treatment of ptosis may therefore be able to avoid a separate procedure for limb muscle biopsy. Further study is required to determine the specificity of these findings.