This paper offers a unified explanation for the slowdown of productivity growth, the decline in business dynamism, and the rise of market power. Using a quantitative framework, I show that the rise of intangible inputs, such as software, can explain these trends. Intangibles reduce marginal costs and raise fixed costs, which gives firms with high-intangible adoption a competitive advantage, in turn deterring other firms from entering. I structurally estimate the model on French and US micro data. After initially boosting productivity, the rise of intangibles causes a decline in productivity growth, consistent with the empirical trends observed since the mid-1990s.

Does UN peacekeeping promote democracy in countries wracked by civil war? Existing studies are limited and reach contradictory conclusions. We develop a theory to explain how peacekeepers can help overcome obstacles to democratization in conflict-affected countries, then test our theory by combining three original datasets on UN mandates, personnel, and activities covering all UN missions in Africa since the end of the Cold War. Using fixed effects and instrumental variables estimators, we show that UN missions with democracy promotion mandates are strongly positively correlated with the quality of democracy in host countries but that the magnitude of the relationship is larger for civilian than for uniformed personnel, stronger when peacekeepers engage rather than bypass host governments when implementing reforms, driven in particular by UN election administration and oversight, and more robust during periods of peace than during periods of civil war.

Despite the popular narrative that the United States is a “land of mobility,” the country may have become a “rooted America” after a decades-long decline in migration rates. This article interrogates the lingering question about the social forces that limit migration, with an empirical focus on internal migration in the United States. We propose a systemic, network model of migration flows, combining demographic, economic, political, and geographic factors and network dependence structures that reflect the internal dynamics of migration systems. Using valued temporal exponential-family random graph models, we model the network of intercounty migration flows from 2011 to 2015. Our analysis reveals a pattern of segmented immobility, where fewer people migrate between counties with dissimilar political contexts, levels of urbanization, and racial compositions. Probing our model using “knockout experiments” suggests one would have observed approximately 4.6 million (27 percent) more intercounty migrants each year were the segmented immobility mechanisms inoperative. This article offers a systemic view of internal migration and reveals the social and political cleavages that underlie geographic immobility in the United States.

The meaning of randomization tests has become obscure in statistics education and practice over the last century. This article makes a fresh attempt at rectifying this core concept of statistics. A new term—“quasi-randomization test”—is introduced to define significance tests based on theoretical models and distinguish these tests from the “randomization tests” based on the physical act of randomization. The practical importance of this distinction is illustrated through a real stepped-wedge cluster-randomized trial. Building on the recent literature on randomization inference, a general framework of conditional randomization tests is developed and some practical methods to construct conditioning events are given. The proposed terminology and framework are then applied to understand several widely used (quasi-)randomization tests, including Fisher’s exact test, permutation tests for treatment effect, quasi-randomization tests for independence and conditional independence, adaptive randomization, and conformal prediction. Supplementary materials for this article are available online.

Drawing on ethnographic fieldwork in Saint Petersburg (Russia) between 2015 and 2016, this article weaves together gift exchange and affect theory to analyze how low-income Muslim women cultivated sisterly intimacies, a materially mediated and affect-laden form of attachment. Sustained through the practices of giving clothing, food, and other spiritually significant items to one another, sisterly intimacies illuminates not only how the women survived and thrived on the margins of Russian society amid socioeconomic crises and political volatility but also how their material exchanges facilitated their ability to remain continuously oriented toward their community and God while striving for an ethical Muslim life and a favorable afterlife. Sisterly intimacies as a cultural formation also offers a broader glimpse into the affective landscapes of Russia, where indignation about socioeconomic injustices and authoritarianism coexist with a desire for (religious) connectivity, ethical living, and collective world-making. Sisterly intimacies as a mode of relationality and self-making highlights the agentive capacity of intimacy to create worlds for those who struggle to live in ways that they consider meaningful.

Expanding the discussion highlighting the role of slavery in the production of medical knowledge beyond the much more extensively studied Atlantic world and the nineteenth-century US South, this article explores the exploitation of enslaved women’s bodies as clinical subjects in fifteenth-century Iberia. Menstrual disorders figured prominently among “hidden defects” cited in slave warranty suits filed by disgruntled buyers across the late medieval Mediterranean world. Reflective of their heightened interest in female physiology during this period, university-trained male physicians were the expert witnesses most frequently called on to resolve disputes concerning what an enslaved woman’s lack of menses meant. Through a close analysis of “expert” testimony in seven lawsuits filed before the court of the Justicia Civil in Valencia in the 1440s, the slave market emerges as a site offering unparalleled opportunities for physicians to directly touch and probe female genitalia. Insofar as they could be poked and prodded with relative impunity, the bodies of enslaved women bought and sold in late medieval Mediterranean markets were instrumental to the expansion of learned gynecological knowledge.

Visual disabilities significantly impact an individual’s mental health. Little is known about the prospective relationship between visual disabilities and anxiety disorders and the underlying effects of modifiable risk factors. Our analysis was based on 117,252 participants from the U.K. Biobank, with baseline data collected between 2006 and 2010. Habitual visual acuity was measured by a standardized logarithmic chart, and ocular disorders reported using questionnaires were collected at baseline. Incident hospitalized anxiety recorded using longitudinal linkage with hospital inpatient data, lifetime anxiety disorder, and current anxiety symptoms assessed by a comprehensive online mental health questionnaire were identified over a 10-year follow-up. After adjustments for confounding factors, one-line worse visual acuity (0.1 logarithm of the minimum angle of resolution [logMAR]) was associated with an increased risk of incident hospitalized anxiety (HR = 1.05, 95% CI = 1.01–1.08), lifetime anxiety disorder (OR = 1.07, 95% CI [1.01–1.12]), and current anxiety scores (β = 0.028, 95% CI [0.002–0.054]). Besides poorer visual acuity, the longitudinal analysis also supported that each ocular disorder (including cataracts, glaucoma, macular degeneration, and diabetes-related eye disease) was significantly associated with at least two anxiety outcomes. Mediation analyses highlighted that subsequent onsets of eye diseases, especially cataracts, and lower socioeconomic status (SES) partly mediated the association between poorer visual acuity and anxiety disorders. This study demonstrates an overall association between visual disabilities and anxiety disorders in middle-aged and older adults. In particular, early interventions involving treatments for visual disabilities and effective psychological counseling services sensitive to socioeconomic status may help prevent anxiety in those living with poor vision.