Advances In Quantitative Methods Research Articles

Quantitative Methods to Detect Suicide and Self-Harm Clusters: A Systematic Review

Suicide and self-harm clusters exist in various forms, including point, mass, and echo clusters. The early identification of clusters is important to mitigate contagion and allocate timely interventions. A systematic review was conducted to synthesize existing evidence of quantitative analyses of suicide and self-harm clusters. Electronic databases including Medline, Embase, Web of Science, and Scopus were searched from date of inception to December 2020 for studies that statistically analyzed the presence of suicide or self-harm clusters. Extracted data were narratively synthesized due to heterogeneity among the statistical methods applied. Of 7268 identified studies, 79 were eligible for narrative synthesis. Most studies quantitatively verified the presence of suicide and self-harm clusters based on the scale of the data and type of cluster. A Poisson-based scan statistical model was found to be effective in accurately detecting point and echo clusters. Mass clusters are typically detected by a time-series regression model, although limitations exist. Recently, the statistical analysis of suicide and self-harm clusters has progressed due to advances in quantitative methods and geospatial analytical techniques, most notably spatial scanning software. The application of such techniques to real-time surveillance data could effectively detect emerging clusters and provide timely intervention.

Quantifying flexibility in thought: The resiliency of semantic networks differs across the lifespan

Older adults tend to have a broader vocabulary compared to younger adults – indicating a richer storage of semantic knowledge – but their retrieval abilities decline with age. Recent advances in quantitative methods based on network science have investigated the effect of aging on semantic memory structure. However, it is yet to be determined how this aging effect on semantic memory structure relates to its overall flexibility. Percolation analysis provides a quantitative measure of the flexibility of a semantic network, by examining how a semantic memory network is resistant to “attacks” or breaking apart. In this study, we incorporated percolation analyses to examine how semantic networks of younger and older adults break apart to investigate potential age-related differences in language production. We applied the percolation analysis to 3 independent sets of data (total N = 78 younger, 78 older adults) from which we generated semantic networks based on verbal fluency performance. Across all 3 datasets, the percolation integrals of the younger adults were larger than older adults, indicating that older adults' semantic networks were less flexible and broke down faster than the younger adults'. Our findings provide quantitative evidence for diminished flexibility in older adults' semantic networks, despite the stability of semantic knowledge across the lifespan. This may be one contributing factor to age-related differences in language production.

The Stock-Bond Correlation

Investors rely on the stock-bond correlation for a variety of tasks, such as forming optimal portfolios, designing hedging strategies, and assessing risk. Most investors estimate the stock–bond correlation simply by extrapolating the historical correlation of monthly returns; they assume that this correlation best characterizes the correlation of future annual or multiyear returns, but this approach is decidedly unreliable. The authors introduce four innovations for generating a reliable prediction of the stock-bond correlation. First, they show how to represent the correlation of single-period cumulative stock and bond returns in a way that captures how the returns drift during the period. Second, they identify fundamental predictors of the stock-bond correlation. Third, they model the stock–bond correlation as a function of the path of some fundamental predictors rather than single observations. Finally, they censor their sample to include only relevant observations, in which relevance has a precise mathematical definition. <b>TOPICS:</b>Portfolio management/multi-asset allocation, risk management, statistical methods <b>Key Findings</b> ▪ The stock-bond correlation is a critical component of many investment activities, such as forming optimal portfolios, designing hedging strategies, and assessing risk. ▪ Most investors estimate the correlation of longer-interval returns by extrapolating the correlation of past shorter-interval returns, but this approach is decidedly unreliable. ▪ By applying recent advances in quantitative methods, it is possible to generate reliable predictions of the correlation of longer-horizon stock and bond returns.

Unmixing detrital geochronology age distributions

AbstractDespite recent advances in quantitative methods of detrital provenance analysis, there is currently no widely accepted method of unmixing detrital geochronology age distributions. We developed a model that determines mixing proportions for source samples through inverse Monte Carlo modeling, wherein mixed samples are compared to randomly generated combinations of source distributions, and a range of best mixing proportions are retained. Results may then be used to constrain a forward optimization routine to find a single best‐fit mixture. Quantitative comparison is based on the Kolmogorov‐Smirnov (KS) testDstatistic and Kuiper testVstatistic for cumulative distribution functions, and the Cross‐correlation coefficient for finite mixture distributions (probability density plots or kernel density estimates). We demonstrate the capacity of this model through a series of tests on synthetic data, and published empirical data from North America mixed in known proportions; this proof‐of‐concept testing shows the model is capable of accurately unmixing highly complex distributions. We apply the model to two published empirical data sets mixed in unknown proportions from Colombia and central China. Neither example yields perfect model fits, which provides a cautionary note of potentially inadequate characterization of source and/or mixed samples, and highlights the importance of such characterization for accurate interpretation of sediment provenance. Sample size appears to be a major control on mixture model results; small (n &lt; 100) samples may lead to misinterpretation. The model is available as a MATLAB‐based stand‐alone executable (.exe file) graphical user interface.

Introduction to the Special Issue: Advances in Quantitative Methods to Further Research in Education and Educational Psychology

This article introduces the special issue titled “Advances in Quantitative Research Methods to Further Research in Education and Educational Psychology.” It starts by framing the context for the contributions to the special issue by highlighting some important signposts that marked the development of analytic methods facilitating inferences on change and change processes. Next it underlines how the analytic methods that are the focus of the articles could help expand further the array of questions that researchers in education and educational psychology are able to tackle. The article concludes by providing brief overviews of the main aspects discussed in each of the 8 contributions included in this special issue.

CPT: Pharmacometrics &amp; Systems Pharmacology Publishes Its 100th Article

CPT: Pharmacometrics & Systems Pharmacology (PSP) was launched in September 2012 and, since then, has published at least one new article every week on average. As a result, the journal has now already reached the milestone of publishing its 100th manuscript,1 which is a rare achievement for a new Open Access journal to reach in such a short period of time. Clearly, the success of PSP demonstrates the tremendous growth of the disciplines of pharmacometrics and systems pharmacology and the need for a journal dedicated to these growing areas of science. Approximately half of the publications have been original research articles. In addition, PSP has published Reviews, Tutorials, Perspectives, Commentaries, Book Reviews, and Editorials (see refs 2,3,4,5,6,7 for examples from each category). Broadly speaking, the content of PSP to date represents a balanced mix between pharmacometrics and systems pharmacology-/physiology-based pharmacokinetics (PBPK). One of the aims of the journal is to facilitate the integration of pharmacometrics and systems pharmacology, and the first examples of the application of such a combined approach in drug development have been published.8 Tutorials were established as a new article type at the launch of PSP and have been a remarkable success, based on the very positive feedback from our readers and the impressive download statistics. To date, eight tutorials have been published (http://www.nature.com/psp/tutorials/index.html), providing practical hands-on introductions to a variety of modeling and simulation methodologies and tools. The Open Access and online format of the journal provides an excellent platform for the free and efficient dissemination of this material to researchers and students worldwide, and over time, the journal should grow into a comprehensive and authoritative educational resource. Tutorials are typically accompanied by example data sets and model codes, enabling the reader to work through the case studies in a “hands-on” manner. We plan to build on this success and have already commissioned a series of new Tutorials for publication in 2014; moreover, we are continuously looking for input on new ideas. Additionally, PSP just released its first podcast, PSPod, which features an interview with Dr Diane Mould discussing the three Tutorials she coauthored with Dr Richard Upton on basic concepts in population modeling, simulation, and model-based drug development (http://www.nature.com/psp/podcast/index.html). PSPod will be a quarterly feature of PSP that will delve into the advances in quantitative methods as applied in pharmacology, physiology, and therapeutics in humans; the next scheduled topics are “Diabetes” and “PBPK.” The quality and the efficiency of peer review are crucial aspects to the success of a journal, and the ~50 distinguished international members of our Editorial Board (http://www.nature.com/psp/editors.html) play a pivotal role in this process. The online nature of PSP provides unique opportunities to communicate Pharmacometrics and Systems Pharmacology science in new and more effective ways to our readers. For example, our aim is that every article is accompanied by readily downloadable model codes to allow readers to replicate the key modeling and simulation steps described in the manuscript. Over time, this collection of example codes should grow into a unique, freely available library of a wide variety of Pharmacometrics and Systems Pharmacology models. Another example illustrating how we strive to serve our readers by utilizing the online features of PSP is the recent introduction of so-called Themed Virtual Issues, which are continuously updated collections of all articles on specific topics, such as Tutorials, Diabetes, Cancer, and PBPK (see e.g., http://www.nature.com/psp/diabetes/index.html). We are committed to building on the successful launch of PSP and to helping it grow further as the leading journal and online publication platform for developing and bridging the disciplines of Pharmacometrics and Systems Pharmacology. We hope that this will not only stimulate scientific and methodological innovation but also contribute to broader application and better integration of model-based approaches in drug discovery and development. As mentioned before,9 the ultimate measure of success of these efforts will be a demonstrable increase in the impact of integrated Pharmacometrics and Systems Pharmacology approaches on pharmaceutical innovation and the delivery of new medicines to patients in areas of high medical need.

The developmental psychopathology of alcohol use and alcohol disorders: research achievements and future directions.

The last 25 years have seen significant advances in our conceptualization of alcohol use and alcohol use disorders within a developmental framework, along with advances in our empirical understanding that have been potentiated by advances in quantitative methods. These include advances in understanding the heterogeneity of trajectories of alcohol outcomes; new insights about early childhood antecedents, and adolescence and emerging adulthood as important developmental periods for alcohol outcomes; a more nuanced understanding of the influences of developmental transitions, and their timing and contexts; a greater appreciation for the importance of considering multiple levels of analysis (including an increasing number of genetically informative studies); a continuing focus on studying multiple pathways underlying alcohol outcomes; and an increasing focus on studying the effects of alcohol exposure on future development. The current paper reviews these advances and suggests directions for future study.

High-resolution imaging of selenium in kidneys: a localized selenium pool associated with glutathione peroxidase 3.

Recent advances in quantitative methods and sensitive imaging techniques of trace elements provide opportunities to uncover and explain their biological roles. In particular, the distribution of selenium in tissues and cells under both physiological and pathological conditions remains unknown. In this work, we applied high-resolution synchrotron X-ray fluorescence microscopy (XFM) to map selenium distribution in mouse liver and kidney. Liver showed a uniform selenium distribution that was dependent on selenocysteine tRNA([Ser]Sec) and dietary selenium. In contrast, kidney selenium had both uniformly distributed and highly localized components, the latter visualized as thin circular structures surrounding proximal tubules. Other parts of the kidney, such as glomeruli and distal tubules, only manifested the uniformly distributed selenium pattern that co-localized with sulfur. We found that proximal tubule selenium localized to the basement membrane. It was preserved in Selenoprotein P knockout mice, but was completely eliminated in glutathione peroxidase 3 (GPx3) knockout mice, indicating that this selenium represented GPx3. We further imaged kidneys of another model organism, the naked mole rat, which showed a diminished uniformly distributed selenium pool, but preserved the circular proximal tubule signal. We applied XFM to image selenium in mammalian tissues and identified a highly localized pool of this trace element at the basement membrane of kidneys that was associated with GPx3. XFM allowed us to define and explain the tissue topography of selenium in mammalian kidneys at submicron resolution.

Pathways to Early Coital Debut for Adolescent Girls: A Recursive Partitioning Analysis

This study examined pathways to early coital debut among early to middle adolescent girls in the United States. In a two-year longitudinal study of 104 adolescent girls, recursive partitioning (RP) analyses were conducted to examine the specific factors that were related to engaging in first intercourse by the 10th grade among adolescent girls who had not yet engaged in sexual intercourse by the 8th grade. RP analyses identified subsamples of girls who had low, medium, and high likelihoods of engaging in early coital debut based on six variables (i.e., school aspirations, early physical intimacy experiences, depression, body objectification, body image, and relationship inauthenticity). For example, girls in the lowest likelihood group (3% had engaged in sex by the 10th grade) reported no prior experiences with being touched under their clothes, low body objectification, high aspirations to complete graduate education, and low depressive symptoms; girls in the highest likelihood group (75% had engaged in sex by the 10th grade) also reported no prior experiences with being touched under their clothes, but had high levels of body objectification. The implications of these analyses for the development of female adolescent sexuality, as well as for advances in quantitative methods, are discussed.

Quantitative epidemiology: Progress and challenges

This manuscript is derived from a presentation at the 2006 AVEPM – Schwabe Symposium which honoured the 2006 recipient of the Calvin Schwabe Award – Dr. S. Wayne Martin. Throughout his career, Dr. Martin was instrumental in furthering the development of quantitative epidemiology. This manuscript highlights some of the recent advances in quantitative methods used in veterinary epidemiology and identifies some of the challenges we still face in the use of these methods. Areas discussed are: methods for analyzing hierarchical data, Bayesian methods, survival analysis and integrating causal thinking and statistical analyses.

Recent advances in quantitative methods in Cancer and Human Health Risk Assessment Edler L, Kitsos CP (2005) ISBN: 0470857564; 463 pages; £70.00, €112.50, $105.00 Wiley; http://www.wiley.com/

<b>Recent advances in quantitative methods in Cancer and Human Health Risk Assessment</b> Edler L, Kitsos CP (2005) <i>ISBN: 0470857564; 463 pages; £70.00, €112.50, $105.00</i> Wiley; http://www.wiley.com/

Experience and Expression in the Fear of Crime

We believe that advances in quantitative methods regarding fear of crime can and should be made. Following in a line of research going back nearly a decade (Farrall et al. 1997; Farrall, 2002; Farrall & Gadd, 2004; Jackson, 2004; Jackson et al. 2007) our Working Papers have assessed the everyday experience of fear of crime (i.e. events of worry and visceral feelings which manifest in people's daily lives). By drawing upon data from the 2003/2004 BCS - which fielded new measures of the fear of crime alongside standard items - we have shown that some individuals who say they are worried about crime do not actually worry as part of their everyday life. In this final Working Paper we begin by summarising previous findings. We then move to examining our broad theoretical framework which we outlined in Working Paper 5 and explored using qualitative data in Working Paper 6. To examine our framework we use data from (a) the 03/04 BCS and (b) a relatively small-scale survey from an earlier and separate study of ours (Jackson, 2004; Jackson & Sunshine, 2007).

The natural history of cigarette smoking from adolescence to adulthood in a midwestern community sample: Multiple trajectories and their psychosocial correlates.

Previous research on the natural history of smoking has focused on overall group trajectories without considering the possibility of risk subgroup variation. To address this limitation, the authors of the present study aimed to identify subgroups with varying trajectories of smoking behavior. The authors accomplished this within a cohort-sequential study of a large community sample (N = 8,556) with measurements spanning ages 11-31. After removing 2 a priori groups (abstainers and erratics), the authors empirically identified 4 trajectory groups--early stable smokers, late stable smokers, experimenters, and quitters--and psychosocial variables from adolescence and young adulthood were significantly distinguished among them. Given recent advances in quantitative methods, it is now feasible to consider subgroups of trajectories within an overall longitudinal design.