North Carolina State University

About: North Carolina State University is a education organization based out in Raleigh, North Carolina, United States. It is known for research contribution in the topics: Population & Thin film. The organization has 44161 authors who have published 101744 publications receiving 3456774 citations. The organization is also known as: NCSU & North Carolina State University at Raleigh.

PERSIANN-CDR: Daily Precipitation Climate Data Record from Multisatellite Observations for Hydrological and Climate Studies

Abstract: A new retrospective satellite-based precipitation dataset is constructed as a climate data record for hydrological and climate studies. Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks–Climate Data Record (PERSIANN-CDR) provides daily and 0.25° rainfall estimates for the latitude band 60°S–60°N for the period of 1 January 1983 to 31 December 2012 (delayed present). PERSIANN-CDR is aimed at addressing the need for a consistent, long-term, high-resolution, and global precipitation dataset for studying the changes and trends in daily precipitation, especially extreme precipitation events, due to climate change and natural variability. PERSIANN-CDR is generated from the PERSIANN algorithm using GridSat-B1 infrared data. It is adjusted using the Global Precipitation Climatology Project (GPCP) monthly product to maintain consistency of the two datasets at 2.5° monthly scale throughout the entire record. Three case studies for testing the efficacy of the dataset ...

Estimating F-statistics.

Abstract: ▪ Abstract A moment estimator of θ, the coancestry coefficient for alleles within a population, was described by Weir & Cockerham in 1984 (100) and is still widely cited. The estimate is used by population geneticists to characterize population structure, by ecologists to estimate migration rates, by animal breeders to describe genetic variation, and by forensic scientists to quantify the strength of matching DNA profiles. This review extends the work of Weir & Cockerham by allowing different levels of coancestry for different populations, and by allowing non-zero coancestries between pairs of populations. All estimates are relative to the average value of θ between pairs of populations. Moment estimates for within- and between-population θ values are likely to have large sampling variances, although these may be reduced by combining information over loci. Variances also decrease with the numbers of alleles at a locus, and with the numbers of populations sampled. This review also extends the work of Weir ...

Role of Built Environments in Physical Activity, Obesity, and Cardiovascular Disease

Abstract: There is a growing consensus that large changes in population levels of physical activity and other behaviors required to improve cardiovascular health will require major modifications in environments and policies. Ecological models are the conceptual basis for comprehensive interventions that emphasize environmental and policy changes and that can have widespread and sustainable effects. These interventions are complemented with individual education and motivation and efforts to change social support and norms. Physical activity-specific ecological models indicate which environmental factors are expected to be related to physical activity in multiple life domains: Leisure/recreation/exercise, occupation (school for youth), transportation, and household. Over the past decade, a proliferation of interdisciplinary research has generally supported hypotheses derived from ecological models and identified specific built environment attributes and combinations of attributes that are related to physical activity, mainly for recreation and transportation purposes, and obesity. It is becoming clear that racial/ethnic minority and low-income communities are disadvantaged in access to recreation facilities, positive aesthetics, and protection from traffic. These results provide an empirical rationale for intervention. There are recent examples of environmental changes or community-wide multilevel interventions that had positive effects on physical activity or obesity. Continuing research needs are to improve the rigor of study designs, confirm subgroup- or context-specific built environment associations, identify optimal combinations of attributes, improve understanding of the policy change processes required to achieve environmental changes, and evaluate multilevel interventions. Both research teams and community-based initiatives are collaborating with a wide range of professionals and sectors of society, such as recreation, transportation, city planning, architecture, landscape architecture, geography, criminal justice, and law, in addition to health professionals and behavioral scientists. These diverse teams have stimulated innovations in research, new approaches to intervention, and improved connections with decision makers who can make environment and policy changes in nonhealth sectors of society. The practice of physical activity promotion, obesity prevention, and CVD risk reduction has changed to reflect the shift to multilevel interventions. Major foundations and public health agencies are implementing community-based interventions targeting environment and policy change. Continuing challenges for these community-wide interventions are to maintain support for the multisector, long-term efforts required to change environments, evaluate interventions so they become ever more evidence-based, and integrate explicit chronic disease prevention objectives into professional practices of diverse disciplines, government agencies, and industries whose primary work can affect physical activity and health. Among the largest initiatives was the Centers for Disease Control and Prevention's Communities Putting Prevention to Work grant program, which awarded more than $250 million in 2010 to change environments and policies to improve nutrition and physical activity and prevent obesity. Recommended strategies were based on MAPPS: Media, Access, Point of decision information, Price, and Social support/services. Strategies ranged from improving physical activity in school physical education (access) to subsidizing memberships to recreational facilities (price) to promoting safe routes to school (eg, social support/services). Experience with these initiatives, as well as systematic evaluations, will lead to a better understanding of how to accomplish policy and environmental change in diverse communities and provide important information about the impact of these changes. Language: en

The power of outliers (and why researchers should ALWAYS check for them)

Abstract: There has been much debate in the literature regarding what to do with extreme or influential data points. The goal of this paper is to summarize the various potential causes of extreme scores in a data set (e.g., data recording or entry errors, motivated mis-reporting, sampling errors, and legitimate sampling), how to detect them, and whether they should be removed or not. Another goal of this paper was to explore how significantly a small proportion of outliers can affect even simple analyses. The examples show a strong beneficial effect of removal of extreme scores. Accuracy tended to increase significantly and substantially, and errors of inference tended to drop significantly and substantially once extreme scores were removed. The presence of outliers can lead to inflated error rates and substantial distortions of parameter and statistic estimates when using either parametric or nonparametric tests (e.g., Zimmerman, 1994, 1995, 1998). Casual observation of the literature suggests that researchers rarely report checking for outliers of any sort. This inference is supported empirically by Osborne, Christiansen, and Gunter (2001), who found that authors reported testing assumptions of the statistical procedure(s) used in their studies--including checking for the presence of outliers--only 8% of the time. Given what we know of the importance of assumptions to accuracy of estimates and error rates, this in itself is alarming. There is no reason to believe that the situation is different in other social science disciplines. What are Outliers and Fringeliers and why do we care about them?