We develop a Bayesian model-based approach to finite population estimation accounting for spatialdependence. Our innovation here is a framework that achieves inference for finite population quantities inspatial process settings. A key distinction from the small area estimation setting is that we analyze finitepopulations referenced by their geographic coordinates (point-referenced data). Specifically, we consider atwo-stage sampling design in which the primary units are geographic regions, the secondary units arepoint-referenced locations, and the measured values are assumed to be a partial realization of a spatialprocess. Traditional geostatistical models do not account for variation attributable to finite populationsampling designs, which can impair inferential performance. On the other hand, design-based estimateswill ignore the spatial dependence in the finite population. This motivates the introduction of geostatisticalprocesses that will enable inference at arbitrary locations in our domain of interest. We demonstrate usingsimulation experiments that process-based finite population sampling models considerably improve modelfit and inference over models that fail to account for spatial correlation. Furthermore, the process basedmodels offer richer inference with spatially interpolated maps over the entire region. We reinforce theseimprovements and demonstrate scaleable inference for groundwater Nitrate levels in the population ofCalifornia Central Valley wells by offering estimates of mean Nitrate levels and their spatially interpolatedmaps.

Background

Obesity rates among children and adults continue to accelerate in the U.S., particularly among marginalized and low-income populations. Obesity prevention and reduction policies can significantly impact population health by improving environmental conditions and increasing access to health-promoting resources. Limited research has been conducted to examine state obesity policy change over time. The primary aim of this study is to examine legislative approaches used to prevent and reduce obesity in the state of California (U.S.).

Methods

We used quantitative policy surveillance methods to develop a state database of obesity-related legislation (bills, resolutions) introduced in California's legislature between 1999 and 2020. Descriptive statistics were used to examine trends of introduced and enacted policy by legislative and policy characteristics. Chi-square tests were used to determine differences in characteristics between enacted and non-enacted legislation. Legislative session and policy characteristics found to be associated with enactment were used to predict adoption in a logistic regression.

Results

A total of 284 obesity-related bills and resolutions were introduced in California's legislature between 1999 and 2020 with a peak of 43 in 2005-2006. On average, 25.8 bills and resolutions were introduced each 2-year legislative cycle. Findings indicate that (a) children and schools were the most frequently specified population and setting; (b) the most common policy topics were nutrition (45%) and physical activity (33%); and (c) only 15% of legislation mentioned race/ethnicity. Overall, 24.9% of bills were enacted compared to 82.1% of resolutions adopted. Legislation to raise awareness about obesity had 5.4 times the odds of being passed compared to other topics. Yet this difference was not statistically significant in a sensitivity analysis when we excluded resolutions.

Conclusions

This database can be leveraged to advance our knowledge of effective and equitable policy instruments to prevent and reduce obesity. Results reveal important policy elements that may impact legislative success, including policy topic, and contribute to a nascent evidence base for public health law research, legal epidemiology, and practice. Future work should investigate the role of policy effectiveness research and evidence on legislative policymaking.

The adaptive significance of zebra stripes has thus far eluded understanding. Many explanations have been suggested, including social cohesion, thermoregulation, predation evasion and avoidance of biting flies. Identifying the associations between phenotypic and environmental factors is essential for testing these hypotheses and substantiating existing experimental evidence. Plains zebra striping pattern varies regionally, from heavy black and white striping over the entire body in some areas to reduced stripe coverage with thinner and lighter stripes in others. We examined how well 29 environmental variables predict the variation in stripe characteristics of plains zebra across their range in Africa. In contrast to recent findings, we found no evidence that striping may have evolved to escape predators or avoid biting flies. Instead, we found that temperature successfully predicts a substantial amount of the stripe pattern variation observed in plains zebra. As this association between striping and temperature may be indicative of multiple biological processes, we suggest that the selective agents driving zebra striping are probably multifarious and complex.

This study assessed the consistency of moderate to vigorous physical activity (MVPA) in a sample of middle school physical education lessons. Random intercept hierarchical linear regressions were employed to model the relationship between consistency of MVPA and independent variables, including lesson and teacher characteristics. Larger classes spent significantly more time in consistent MVPA in the absence of controlling for teacher characteristics. A significant interaction between class size and teacher experience suggests that experience may play a beneficial role in larger classes, and overall class size does not have to be a barrier to achieving high levels of MVPA.

BACKGROUND:Physical education (PE) can provide opportunities to engage in daily moderate-to-vigorous physical activity (MVPA), but MVPA levels in many classes are low. This study examines MVPA during middle school PE lessons before and after receiving the SPARK (Sports, Play, and Active Recreation for Kids) program. METHODS:Sixteen schools were enrolled in the study. PE teachers at eight schools received the intervention. PE lessons at all schools (N = 561) were observed over 2 years. Hierarchical linear regression models examined the effect of the intervention on the amount and consistency of MVPA and sedentary behavior. RESULTS:An average of 13.7% of observed class time was spent in MVPA (approximately 5 minutes of a 60-minute class), compared to 27.5% of time spent sedentary. There was no evidence that the curriculum resulted in increased MVPA or consistent MVPA, or that it decreased sedentary behavior. Findings also suggested that contextual factors may contribute to physical activity levels in PE. CONCLUSIONS:Mixed evaluation findings of the SPARK middle school curriculum demonstrate that an out-of-the-box curriculum does not have the same results in all contexts. Implications for school health are described based upon findings. Further research is needed to identify effective strategies to increase MVPA for adolescents both in and outside of PE.

Purpose: This study examines the effects of the middle school SPARK physical education (PE) curriculum on predisposing, enabling, and reinforcing factors for physical activity (PA) as well as self-reported PA in a predominantly low-income, Latinx student population in Los Angeles, CA. Methods: Data were collected from 3763 students of seventh and eighth grades at 2 time points at the 16 middle schools enrolled in the study. Hierarchical logistic regression models were used to assess intervention effects on PA attitudes, PE enjoyment, FitnessGram passing, daily PA, and muscle-strengthening PA, controlling for demographic variables. Results: Although there was no detectable intervention effect on increasing the number of students exercising 60 minutes per day, there was a negative intervention effect detected for muscle-strengthening exercises. A significant positive intervention effect was detected for both PE enjoyment and FitnessGram passing. Deeper analysis of these findings revealed that the positive effect on PE enjoyment occurred only among male students. Conclusion: The SPARK curriculum had mixed effects on students' PA behavior as well as predisposing, enabling, and reinforcing factors for PA. Incorporating student perspectives into the evaluation of intervention efforts to promote PA can facilitate a better understanding of the ways in which these efforts influence PA behaviors and its determinants.

The purpose of this study was to examine the determinants of benefits and barriers and their relationship with physical activity (PA) among predominantly Latino middle school students. Data were collected in a cross-sectional survey of 4,773 seventh-grade students recruited from a large, urban school district in Los Angeles. Hierarchical logistic regression models were used to assess determinants of benefits and barriers as well as their association with self-reported PA. Differences in benefits and barriers were observed by gender, ethnicity, and body size. Barriers were negatively correlated with all three PA outcomes while benefits were positively associated with exercising at least 60 min daily. A deeper understanding of benefits and barriers can facilitate the development of interventions and collaborative efforts among physical education teachers, school nurses, and administrators to implement comprehensive approaches that encourage students' participation in PA inside and outside of the classroom.

Urban food swamps are typically situated in low-income, minority communities and contribute to overweight and obesity. Changing the food landscape in low income and underserved communities is one strategy to combat the negative health consequences associated with the lack of access to healthy food resources and an abundance of unhealthy food venues. In this paper, we describe Proyecto MercadoFRESCO (Fresh Market Project), a corner store intervention project in East Los Angeles and Boyle Heights in California that used a multi-level approach with a broad range of community, business, and academic partners. These are two neighboring, predominantly Latino communities that have high rates of overweight and obesity. Located in these two communities are approximately 150 corner stores. The project used a community-engaged approach to select, recruit, and convert four corner stores, so that they could become healthy community assets in order to improve residents' access to and awareness of fresh and affordable fruits and vegetables in their immediate neighborhoods. We describe the study framework for the multi-level intervention, which includes having multiple stakeholders, expertise in corner store operations, community and youth engagement strategies, and social marketing campaigns. We also describe the evaluation and survey methodology to determine community and patron impact of the intervention. This paper provides a framework useful to a variety of public health stakeholders for implementing a community-engaged corner store conversion, particularly in an urban food swamp.

Background

The employment of professional interviewers from academic survey centers to conduct surveys has been standard practice. Because one goal of community-engaged research is to provide professional skills to community residents, this paper considers whether employing locally trained lay interviewers from within the community may be as effective as employing interviewers from an academic survey center with regard to unit and item nonresponse rates and cost.

Methods

To study a nutrition-focused intervention, 1035 in-person household interviews were conducted in East Los Angeles and Boyle Heights, 503 of which were completed by lay community interviewers. A chi-square test was used to assess differences in unit nonresponse rates between professional and community interviewers and Welch's t tests were used to assess differences in item nonresponse rates. A cost comparison analysis between the two interviewer groups was also conducted.

Results

Interviewers from the academic survey center had lower unit nonresponse rates than the lay community interviewers (16.2% vs. 23.3%; p < 0.01). However, the item nonresponse rates were lower for the community interviewers than the professional interviewers (1.4% vs. 3.3%; p < 0.01). Community interviewers cost approximately $415.38 per survey whereas professional interviewers cost approximately $537.29 per survey.

Conclusions

With a lower cost per completed survey and lower item nonresponse rates, lay community interviewers are a viable alternative to professional interviewers for fieldwork in community-based research. Additional research is needed to assess other important aspects of data quality interviewer such as interviewer effects and response error.

Background

A substantial proportion of adolescents, particularly girls and minority youth, fail to meet daily physical activity (PA) recommendations. Social support contributes to adolescent PA, but studies examining this relationship have yielded inconsistent results and rarely focus on diverse, urban populations.

Aims

This study examines the correlates of support for PA from family and friends and its relationship with PA outcomes among young adolescents.

Methods

Data were collected in a cross-sectional survey of 4,773 middle school students. Social support from family and friends was separately measured using the Sallis Support for Exercise Scales. Hierarchical logistic regression models were used to assess correlates of high support and the relationship between support and self-reported PA.

Results

Approximately one quarter of students reported being active for at least an hour each day. 31.7% of students reported high family support for PA, while 17.8% reported high friend support. Differences in perceptions of support by gender, ethnicity, and language emerged. Support from family and friends were both consistently strong predictors of all three PA outcomes measured.

Discussion

Findings highlight the need for multilevel interventions targeting both psychosocial influences on behavior in addition to addressing the physical environment. Given low rates of friend support for PA, there appears to be an opportunity to increase PA levels through promotion of supportive behaviors among peers.

Conclusion

Support for PA from family and friends is a key contributor to increased PA among adolescents. Further research is needed to further understand the mechanisms by which these factors influence PA.