Racial Differences in Activity Space Exposures and Everyday Perceptions of Safety Among Urban Youth.

PURPOSE: The everyday experience of safety promotes health and successful development during adolescence. To date, few studies have examined racial variation in the spatial determinants of in-the-moment perceived safety. METHODS: Drawing on data from the Columbus, Ohio-based Adolescent Health and Development in Context study (N = 1,405), we consider the influence of intraindividual variability in Global Positioning System-based exposure to both high-proportion White urban neighborhoods and neighborhood violence for the everyday location-based safety perceptions of Black and White youth (ages 11-17) as captured by ecological momentary assessment. RESULTS: Exposure to higher area-level violence reduces youths' safety perceptions. Momentary exposure to residentially White-dominated neighborhoods also reduces perceived safety, but only for Black youth who spend more time, on average, in White areas. In contrast, we observe some limited evidence that White youth perceive greater safety when in White neighborhoods if they spend more time in white neighborhoods on average. DISCUSSION: These findings point to the need for greater attention to in situ experiences in understanding the origins of racial disparities in health and wellbeing. For Black youth, a restricted focus on the consequences of residing in Black segregated neighborhoods may obscure potentially health consequential exposures beyond these areas.

Statistical inference for complete and incomplete mobility trajectories under the flight-pause model.

We formulate a statistical flight-pause model (FPM) for human mobility, represented by a collection of random objects, called motions, appropriate for mobile phone tracking (MPT) data. We develop the statistical machinery for parameter inference and trajectory imputation under various forms of missing data. We show that common assumptions about the missing data mechanism for MPT are not valid for the mechanism governing the random motions underlying the FPM, representing an understudied missing data phenomenon. We demonstrate the consequences of missing data and our proposed adjustments in both simulations and real data, outlining implications for MPT data collection and design.

Everyday perceptions of safety and racial disparities in hair cortisol concentration.

OBJECTIVE: Black-White disparities in physiological stress during adolescence are increasingly evident but remain incompletely understood. We examine the role of real-time perceptions of safety in the context of everyday routines to gain insight into the sources of observed adolescent racial differences in chronic stress as measured by hair cortisol concentration (HCC). METHOD: We combined social survey, ecological momentary assessment (EMA), and hair cortisol data on 690 Black and White youth ages 11-17 from wave 1 of the Adolescent Health and Development in Context (AHDC) study to investigate racial differences in physiological stress. Individual-level, reliability-adjusted measures of perceived unsafety outside the home were drawn from a week-long smartphone-based EMA and tested for association with hair cortisol concentration. RESULTS: We observed a statistically significant interaction (p < .05) between race and perceptions of unsafety. For Black youth, perceived unsafety was associated with higher HCC (p < .05). We observed no evidence of an association between perceptions of safety and expected HCC for White youth. For youth who perceive their out-of-home activity locations to be consistently safe, the racial difference in expected HCC was not statistically significant. At the high end of perceived unsafety, however, Black-White differences in HCC were pronounced (0.75 standard deviations at the 95th percentile on perceived unsafety; p < .001). DISCUSSION: These findings call attention to the role of everyday perceptions of safety across non-home routine activity contexts in explaining race differences in chronic stress as assessed by hair cortisol concentrations. Future research may benefit from data on in situ experiences to capture disparities in psychological and physiological stress.

Paws on the Street: Neighborhood-Level Concentration of Households with Dogs and Urban Crime.

The formative work of Jane Jacobs underscores the combination of "eyes on the street" and trust between residents in deterring crime. Nevertheless, little research has assessed the effects of residential street monitoring on crime due partly to a lack of data measuring this process. We argue that neighborhood-level rates of households with dogs captures part of the residential street monitoring process core to Jacobs' hypotheses and test whether this measure is inversely associated with property and violent crime rates. Data from a large-scale marketing survey of Columbus, OH, USA residents (2013; n = 43,078) are used to measure census block group-level (n = 595) rates of households with dogs. Data from the Adolescent Health and Development in Context study are used to measure neighborhood-level rates of trust. Consistent with Jacobs' hypotheses, results indicate that neighborhood concentration of households with dogs is inversely associated with robbery, homicide, and, to a less consistent degree, aggravated assault rates within neighborhoods high in trust. In contrast, results for property crime suggest that the inverse association of dog concentration is independent of levels of neighborhood trust. These associations are observed net of controls for neighborhood sociodemographic characteristics, temporally lagged crime, and spatial lags of trust and dog concentration. This study offers suggestive evidence of crime deterrent benefits of local street monitoring and dog presence and calls attention to the contribution of pets to other facets of neighborhood social organization.

RESTRICTED SPATIAL REGRESSION METHODS: IMPLICATIONS FOR INFERENCE.

The issue of spatial confounding between the spatial random effect and the fixed effects in regression analyses has been identified as a concern in the statistical literature. Multiple authors have offered perspectives and potential solutions. In this paper, for the areal spatial data setting, we show that many of the methods designed to alleviate spatial confounding can be viewed as special cases of a general class of models. We refer to this class as Restricted Spatial Regression (RSR) models, extending terminology currently in use. We offer a mathematically based exploration of the impact that RSR methods have on inference for regression coefficients for the linear model. We then explore whether these results hold in the generalized linear model setting for count data using simulations. We show that the use of these methods have counterintuitive consequences which defy the general expectations in the literature. In particular, our results and the accompanying simulations suggest that RSR methods will typically perform worse than non-spatial methods. These results have important implications for dimension reduction strategies in spatial regression modeling. Specifically, we demonstrate that the problems with RSR models cannot be fixed with a selection of "better" spatial basis vectors or dimension reduction techniques.

Racial Inequalities in Adolescents' Exposure to Racial and Socioeconomic Segregation, Collective Efficacy, and Violence.

In the United States, Black youth tend to grow up in remarkably less resourced neighborhoods than White youth. This study investigates whether and to what extent Black youth are moreover exposed to less resourced activity spaces beyond the home. We draw on GPS data from a large sample of urban youth in the Columbus, Ohio-based Adolescent Health and Development in Context study (2014-2016) to examine to what extent Black youth experience nontrivial, disproportionate levels of exposure to more disadvantaged and segregated contexts in their daily routines compared with similarly residentially situated White youth. Specifically, we estimate Black-White differences in nonhome exposure to concentrated disadvantage, racial segregation, collective efficacy, and violent crime. We find that Black youths' activity spaces have substantially higher rates of racial segregation and violent crime than those of White youth, and substantially lower levels of collective efficacy-even after accounting for a host of individual- and home neighborhood-level characteristics. We find more modest evidence of differences in exposure to socioeconomic disadvantage. These findings have important implications for neighborhood-centered interventions focused on youth well-being and the contextual effects and segregation literatures more generally.

Geographic Isolation, Compelled Mobility, and Everyday Exposure to Neighborhood Racial Composition Among Urban Youth.

Foundational urban social theories view heterogeneity of exposure to spatial and social contexts as essential aspects of the urban experience. In contrast, contemporary neighborhood research emphasizes the isolation of city dwellers - particularly residents of racially segregated neighborhoods. Using geospatial data on a sample of youth from the 2014-16 Columbus, OH-based Adolescent Health and Development in Context study, we explore the extent to which the neighborhood locations of everyday activities vary with respect to residential racial composition. In the context of segregated US metro areas, the geographic isolation approach expects home census tract racial composition to powerfully shape the racial composition of activity location neighborhoods. In this view, Black youth residing in high proportion Black neighborhoods are expected to spend the vast majority of their time exposed to similarly Black-concentrated neighborhoods. Consistent with an alternative compelled mobility approach, we find that Black youth residing in high proportion Black neighborhoods exhibit among the highest levels of heterogeneity in the racial composition of neighborhoods encountered. Moreover, Black youth residing in high proportion Black neighborhoods are expected to spend 39% of their non-home time (roughly 2.5 hours a day) in low proportion Black neighborhoods compared to 23% (1.5 hours) in high proportion Black neighborhoods. Exposures to low proportion Black neighborhoods among these youth are largely driven by organizationally-based resource seeking. These findings call into question the assumption that residence in Black segregated neighborhoods leads to homogeneously Black segregated neighborhood exposures and encourage theoretical development and data collection strategies that acknowledge the potential for significant heterogeneity in the everyday neighborhood experiences of urban youth.

Activity Locations, Residential Segregation, and the Significance of Residential Neighborhood Boundary Perceptions.

The inadequacies of residential census geography in capturing urban residents' routine exposures have motivated efforts to more directly measure residents' activity spaces. In turn, insights regarding urban activity patterns have been used to motivate alternative residential neighborhood measurement strategies incorporating dimensions of activity space in the form of egocentric neighborhoods-measurement approaches that place individuals at the center of their own residential neighborhood units. Unexamined, however, is the extent to which the boundaries of residents' own self-defined residential neighborhoods compare with census-based and egocentric neighborhood measurement approaches in aligning with residents' routine activity locations. We first assess this question, examining whether the boundaries of residents' self-defined residential neighborhoods are in closer proximity to the coordinates of a range of activity location types than are the boundaries of their census and egocentric residential neighborhood measurement approaches. We find little evidence that egocentric or, crucially, self-defined residential neighborhoods better align with activity locations, suggesting a division in residents' activity locations and conceptions of their residential neighborhoods. We then examine opposing hypotheses about how self-defined residential neighborhoods and census tracts compare in socioeconomic and racial composition. Overall, our findings suggest that residents bound less segregated neighborhoods than those produced by census geography, but self-defined residential neighborhoods still reflect a preference toward homophily when considering areas beyond the immediate environment of their residence. These findings underscore the significance of individuals' conceptions of residential neighborhoods to understanding and measuring urban social processes such as residential segregation and social disorganization.

Exposure to police-related deaths and physiological stress among urban black youth.

BACKGROUND: Emerging evidence indicates that exposure to police-related deaths is associated with negative health and wellbeing outcomes among black people. Yet, no study to date has directly examined the biological consequences of exposure to police-related deaths for urban black youth. METHODS AND FINDINGS: We employ unique data from the 2014-16 Adolescent Health and Development in Context (AHDC) study - a representative sample of youth ages 11 to 17 residing in the Columbus, OH area. A subsample of participants contributed nightly saliva samples for cortisol for up to six days, providing an opportunity to link recent exposures to police-related deaths within the residential county to physiological stress outcomes during the study period (N = 585). We examine the effect of exposure to a recent police-related death in the same county on the physiological stress (nightly cortisol) levels of black youth. We find evidence of elevated average levels of nightly cortisol (by 46%) for black boys exposed to a police-related death of a black victim in the 30 days prior to the subject's cortisol collection. We find no evidence of police-related death effects on the physiological stress levels of black girls or white youth. CONCLUSIONS: These analyses indicate that police-related deaths influence the biological functioning of black boys, with potential negative consequences for health. We consider the implications of exposure to lethal police violence among black boys for understanding racial disparities in health more broadly.

Human Mobility and Crime: Theoretical Approaches and Novel Data Collection Strategies.

This review outlines approaches to explanations of crime that incorporate the concept of human mobility-or the patterns of movement throughout space of individuals or populations in the context of everyday routines-with a focus on novel strategies for the collection of geographically referenced data on mobility patterns. We identify three approaches to understanding mobility-crime linkages: (a) Place and neighborhood approaches characterize local spatial units of analysis of varying size with respect to the intersection in space and time of potential offenders, victims, and guardians; (b) person-centered approaches emphasize the spatial trajectories of individuals and person-place interactions that influence crime risk; and (c) ecological network approaches consider links between persons or collectivities based on shared activity locations, capturing influences of broader systems of interconnection on spatial- and individual-level variation in crime. We review data collection strategies for the measurement of mobility across these approaches, considering both the challenges and promise of mobility-based research for criminology.

Neighborhoods, Activity Spaces, and the Span of Adolescent Exposures.

Since the inception of urban sociology, the "neighborhood" has served as the dominant context thought to capture developmentally significant youth experiences beyond the home. Yet no large-scale study has examined patterns of exposure to the most commonly used operationalization of neighborhood - the census tract - among urban youth. Using smartphone GPS data from the Adolescent Health and Development in Context study (N=1405), we estimate the amount of time youth spend in residential neighborhoods and consider explanations for variation in neighborhood exposure. On average, youth (ages 11 to 17) spend 5.7% of their waking time in their neighborhood but not at home, 60% at home, and 34.3% outside their neighborhood. Multilevel negative binomial regression models indicate that residence in economically disadvantaged neighborhoods is associated with less time in neighborhood. Higher levels of local violence and the absence of a neighborhood school the youth is eligible to attend are negatively associated with time in neighborhood and mediate the concentrated disadvantage effect. Fractional multinomial logit models indicate that higher violence is linked with increased time at home while school absence is associated with increased outside-neighborhood time. Theoretical development and empirical research on neighborhood effects should incorporate findings on the extent and nature of neighborhood and broader activity space exposures among urban youth.

Beyond Activity Space: Detecting Communities in Ecological Networks.

Emerging research suggests that the extent to which activity spaces - the collection of an individual's routine activity locations - overlap provides important information about the functioning of a city and its neighborhoods. To study patterns of overlapping activity spaces, we draw on the notion of an ecological network, a type of two-mode network with the two modes being individuals and the geographic locations where individuals perform routine activities. We describe a method for detecting "ecological communities" within these networks based on shared activity locations among individuals. Specifically, we identify latent activity pattern profiles, which, for each community, summarize its members' probability distribution of going to each location, and community assignment vectors, which, for each individual, summarize his/her probability distribution of belonging to each community. Using data from the Adolescent Health and Development in Context (AHDC) Study, we employ latent Dirichlet allocation (LDA) to identify activity pattern profiles and communities. We then explore differences across neighborhoods in the strength, and within-neighborhood consistency of community assignment. We hypothesize that these aspects of the neighborhood structure of ecological community membership capture meaningful dimensions of neighborhood functioning likely to co-vary with economic and racial composition. We discuss the implications of a focus on ecological communities for the conduct of "neighborhood effects" research more broadly.

The timing of geographic power.

In many studies on the spatial risk of disease, investigators use geographic locations at the time of disease diagnosis in spatial models to search for individual areas of elevated risk. However, these studies often fail to find a significant spatial signal. This may be due to the misspecification of the timing and location of pertinent exposures. Environmental exposures related to cancer risk vary over space and time, and many cancers have long latencies. When these factors are considered in conjunction with a mobile population, it is likely that the spatial signal related to relevant historic environmental exposures is obscured. To investigate this hypothesis, we conducted simulation studies to characterize the effect of residential mobility on the ability of generalized additive models to detect areas of significantly elevated historic environmental exposure. We generated data based on the residential histories of participants in the National Cancer Institute Surveillance, Epidemiology, and End Results non-Hodgkin lymphoma study, and varied the duration and intensity of the environmental exposure. Results showed that the probability of detection, mean spatial sensitivity, and mean spatial specificity of models decreased steadily as the time since relevant exposure increased. This suggests that for diseases with long latencies, spatial areas of high risk due to high-intensity exposure of relatively short duration will be difficult to detect over time when using residential locations at the time of diagnosis in mobile study populations.

Feasibility and Validity of Geographically Explicit Ecological Momentary Assessment With Recall-Aided Space-Time Budgets.

We employ data from the Adolescent Health and Development in Context Study-a representative sample of urban youth ages 11-17 in and around the Columbus, OH area-to investigate the feasibility and validity of smartphone-based geographically explicit ecological momentary assessment (GEMA). Age, race, household income, familiarity with smartphones, and self-control were associated with missing global positioning systems (GPS) coverage, whereas school day was associated with discordance between percent of time at home based on GPS-only versus recall-aided space-time budget data. Fatigue from protocol compliance increases missing GPS across the week, which results in more discordance. Although some systematic differences were observed, these findings offer evidence that smartphone-based GEMA is a viable method for the collection of activity space data on urban youth.

Family contexts and sleep during adolescence.

Sleep deprivation among adolescents has received much attention from health researchers and policymakers. Recent research indicates that variation in sleep duration from night to night is associated with multiple health outcomes. While there is evidence that sleep deprivation is socially patterned, we know little about how social contexts are associated with nightly sleep variation during adolescence (a life course stage when nightly sleep variation is particularly high). Given the importance of family environments for influencing adolescents' sleep patterns, we hypothesized that disadvantaged family contexts would be associated with higher intra-individual variation (IIV) in nightly sleep duration, in addition to lower average nightly sleep duration. We tested these hypotheses in a diverse, population-based sample of 11-17 year-olds (N = 1095) from the Adolescent Health and Development in Context Study. Using survey and ecological momentary assessment data and a novel form of multi-level regression modeling (location-scale mixed modeling), we found that adolescents living in unmarried-parent, low SES, economically insecure, and high caregiver stress families had higher IIV in sleep than adolescents in families with more resources and less caregiver stress. There were fewer family effects on average sleep duration. This suggests family social and economic contexts are associated with an under-researched aspect of adolescent sleep, nightly variation, and may contribute to adolescent sleep problems with implications for their health and health disparities.

The Geometry of Continuous Latent Space Models for Network Data.

We review the class of continuous latent space (statistical) models for network data, paying particular attention to the role of the geometry of the latent space. In these models, the presence/absence of network dyadic ties are assumed to be conditionally independent given the dyads' unobserved positions in a latent space. In this way, these models provide a probabilistic framework for embedding network nodes in a continuous space equipped with a geometry that facilitates the description of dependence between random dyadic ties. Specifically, these models naturally capture homophilous tendencies and triadic clustering, among other common properties of observed networks. In addition to reviewing the literature on continuous latent space models from a geometric perspective, we highlight the important role the geometry of the latent space plays on properties of networks arising from these models via intuition and simulation. Finally, we discuss results from spectral graph theory that allow us to explore the role of the geometry of the latent space, independent of network size. We conclude with conjectures about how these results might be used to infer the appropriate latent space geometry from observed networks.

Comment on Article by Bradley, Holan, and Wikle.

We provide a discussion of the article "Computationally Efficient Multivariate Spatio-Temporal Models for High-Dimensional Count-Valued Data" by Bradley, Holan, and Wikle. In our opinion, this work constitutes a major contribution to the field of spatio-temporal statistics and contains distribution theory that should be broadly applicable. In this note, we reflect on modeling decisions made by the authors. We include a small set of simulation results to illustrate the effect of one aspect of the proposed model.

Socioeconomic Segregation of Activity Spaces in Urban Neighborhoods: Does Shared Residence Mean Shared Routines?

Residential segregation by income and education is increasing alongside slowly declining black-white segregation. Segregation in urban neighborhood residents' non-home activity spaces has not been explored. How integrated are the daily routines of people who live in the same neighborhood? Are people with different socioeconomic backgrounds that live near one another less likely to share routine activity locations than those of similar education or income? Do these patterns vary across the socioeconomic continuum or by neighborhood structure? The analyses draw on unique data from the Los Angeles Family and Neighborhood Survey that identify the location where residents engage in routine activities. Using multilevel p2 (network) models, we analyze pairs of households located in the same neighborhood and examine whether the dyad combinations across three levels of SES conduct routine activities in the same location, and whether neighbor socioeconomic similarity in the co-location of routine activities is dependent on the level of neighborhood socioeconomic inequality and trust. Results indicate that, on average, increasing SES diminishes the likelihood of sharing activity locations with any SES group. This pattern is most pronounced in neighborhoods characterized by high levels of socioeconomic inequality. Neighborhood trust explains a nontrivial proportion of the inequality effect on the extent of routine activity sorting by SES. Thus stark, visible neighborhood-level inequality by SES may lead to enhanced effects of distrust on the willingness to share routines across class.

Understanding Racial Differences in Exposure to Violent Areas: Integrating Survey, Smartphone, and Administrative Data Resources.

Emerging evidence indicates that exposure to violent areas may influence youth wellbeing. We employ smartphone GPS data on youth activity spaces to examine the extent of, and potential explanations for, racial disparities in these exposures. Multilevel models of data from the Adolescent Health and Development in Context study indicate that exposures to violent areas vary significantly across days of the week and between youth who reside in the same neighborhood. African American youth are exposed to areas with substantially higher levels of violence. Residing in a disadvantaged neighborhood is significantly associated with exposure to violent areas and explains a non-trivial proportion of the racial difference in this outcome. However, neighborhood factors are incomplete explanations of the racial disparity. Characteristics of the activity locations at which youth spend time explain the residual racial disparity in exposure to violent areas. These findings highlight the importance of youth activity spaces, above and beyond their neighborhood environments.

Ecological Networks and Neighborhood Social Organization.

Drawing on the social disorganization tradition and the social ecological perspective of Jane Jacobs, the authors hypothesize that neighborhoods composed of residents who intersect in space more frequently as a result of routine activities will exhibit higher levels of collective efficacy, intergenerational closure, and social network interaction and exchange. They develop this approach employing the concept of ecological networks-two-mode networks that indirectly link residents through spatial overlap in routine activities. Using data from the Los Angeles Family and Neighborhood Survey, they find evidence that econetwork extensity (the average proportion of households in the neighborhood to which a given household is tied through any location) and intensity (the degree to which household dyads are characterized by ties through multiple locations) are positively related to changes in social organization between 2000-2001 and 2006-2008. These findings demonstrate the relevance of econetwork characteristics-heretofore neglected in research on urban neighborhoods-for consequential dimensions of neighborhood social organization.