Statistical Definition Research Articles

Shuttleworth equation: A molecular simulations perspective.

Even though the study of interfacial phenomena can be traced back to Laplace and was given a solid thermodynamic foundation by Gibbs, it appears that some concepts and relations among them are still causing some confusion and debates in the literature, particularly for interfaces involving solids. In particular, the definitions of the concepts of interfacial tension, free energy, and stress and the relationships between them sometimes lack clarity, and some authors even question their validity. So far, the debates about these relationships, in particular the Shuttleworth equation, have taken place within the framework of classical thermodynamics. In this work, we are offering to look at these concepts within the framework of statistical mechanics, which can be readily tested in Molecular Dynamics (MD) simulations. For a simple one component system of particles interacting via the Lennard-Jones potential, we calculate by the cleaving method the excess free energy of a solid-vacuum interface (solid surface) for systems in different states of tangential strain and compare the results to the calculation of surface stress via the difference of normal and tangential forces at the surface. As a result, we demonstrate consistency, within the statistical uncertainty, of the thermodynamic and statistical mechanical definitions of surface free energy and surface stress and how they are expressed via interaction-dependent quantities in MD simulations.

Social tariffs and democratic choice-Do population-based health state values reflect the will of the people?

In economic evaluations of health technologies, health outcomes are commonly measured in terms of quality-adjusted life years (QALYs). QALYs are the product of time and health-related quality of life. Health-related quality of life, in turn, is determined by a social tariff, which is supposed to reflect the public's preference over health states. This study argues that, because of the tariff's role in the societal decision-making process, it should not be understood as merely an operational (statistical) definition of health, but as a major instrument of democratic participation. I outline what implications this might have for both the method used to aggregate individual preferences, and the set of individuals whose preferences should count. Alternative tariff specifications and decision rules are explored, and future research directions are proposed.

The “Is mpMRI Enough” or IMRIE Study: A Multicentre Evaluation of Prebiopsy Multiparametric Magnetic Resonance Imaging Compared with Biopsy

BackgroundMultiparametric magnetic resonance imaging (mpMRI) is now recommended prebiopsy in numerous healthcare regions based on the findings of high-quality studies from expert centres. Concern remains about reproducibility of mpMRI to rule out clinically significant prostate cancer (csPCa) in real-world settings. ObjectiveTo assess the diagnostic performance of mpMRI for csPCa in a real-world setting. Design, setting, and participantsA multicentre, retrospective cohort study, including men referred with raised prostate-specific antigen (PSA) or an abnormal digital rectal examination who had undergone mpMRI followed by transrectal or transperineal biopsy, was conducted. Patients could be biopsy naïve or have had previous negative biopsies. Outcome measurements and statistical analysisThe primary definition for csPCa was International Society of Urological Pathology (ISUP) grade group (GG) ≥2 (any Gleason ≥7); the accuracy for other definitions was also evaluated. Results and limitationsAcross ten sites, 2642 men were included (January 2011–November 2018). Mean age and PSA were 65.3yr (standard deviation [SD] 7.8yr) and 7.5ng/ml (SD 3.3ng/ml), respectively. Of the patients, 35.9% had “negative MRI” (scores 1–2); 51.9% underwent transrectal biopsy and 48.1% had transperineal biopsy, with 43.4% diagnosed with csPCa overall. The sensitivity and negative predictive value (NPV) for ISUP GG≥2 were 87.3% and 87.5%, respectively. The NPVs were 87.4% and 88.1% for men undergoing transrectal and transperineal biopsy, respectively. Specificity and positive predictive value of MRI were 49.8% and 49.2%, respectively. The sensitivity and NPV increased to 96.6% and 90.6%, respectively, when a PSA density threshold of 0.15ng/ml/ml was used in MRI scores 1–2; these metrics increased to 97.5% and 91.2%, respectively, for PSA density 0.12ng/ml/ml. ISUP GG≥3 (Gleason ≥4+3) was found in 2.4% (15/617) of men with MRI scores 1–2. They key limitations of this study are the heterogeneity and retrospective nature of the data. ConclusionsMultiparametric MRI when used in real-world settings is able to rule out csPCa accurately, suggesting that about one-third of men might avoid an immediate biopsy. Men should be counselled about the risk of missing some significant cancers. Patient summaryMultiparametric magnetic resonance imaging (MRI) is a useful tool for ruling out prostate cancer, especially when combined with prostate-specific antigen density (PSAD). Previous results published from specialist centres can be reproduced at smaller institutions. However, patients and their clinicians must be aware that an early diagnosis of clinically significant prostate cancer could be missed in nearly 10% of patients by relying on MRI and PSAD alone.

The goniomaxillar length/goniomandibular length ratio in normal newborn infants: A clinical tool for defining chin position abnormalities.

Retrognathia (recessed chin) and prognathism (prominent chin) often present as signs of an underlying condition. Accurate clinical definitions are important. Yet their definitions were according to "clinical impression", or to seldom used X-ray criteria. We propose a statistical and anthropometric definition of retrognathia and prognathism based upon the ratio between the goniomaxillar length (distance between the gonion at the mandible angle and the subnasale and the goniomandibular length (distance between the mandible angle and the most anterior point of the bony chin). We assumed that an increase in the ratio indicates retrognathia and a decrease reflects prognathism. We conducted a prospective, observational, anthropometric study in 204 consecutive healthy term infants. Measurements took place on the second day of life, using sliding calipers. Mean ± SD of goniomandibular length (5.1 ± 0.3 cm), goniomaxillar length (5.4 ± 0.3 cm), were calculated. All measurements correlated significantly with gestational age, and with infant birthweight. The mean ± SD goniomaxillar length/goniomandibular length ratio was 1.06 ± 0.05. We defined a normal ratio as being within 2 SD of the mean, that is, between 0.96 and and 1.16. This ratio correlated with neither gestational age nor with birthweight. We conclude that the goniomaxillar length/goniomandibular length ratio can be calculated whenever retro - or prognathism is suspected. A ratio outside of the 95% confidence interval should help in making this diagnosis. An increase in this ratio beyond 2 SD above the mean (1.16) could be interpreted as retrognathia and a decrease beyond 2 SD below the mean (0.96) as prognathism.

Construção de indicadores-padrão para cooperativas agropecuárias de Mato Grosso do Sul

Este estudo teve como objetivo desenvolver, através de índices-padrão, um referencial de comparação para os índices econômico-financeiros das cooperativas agropecuárias do Estado de Mato Grosso do Sul. Trata-se de uma pesquisa quantitativa, descritiva, bibliográfica e documental. Dessa forma, utilizou-se de balanços patrimoniais e demonstrações de sobras e perdas de dezoito cooperativas agropecuárias de Mato Grosso do Sul. A partir desses demonstrativos, foram calculados os indicadores econômico-financeiros dessas entidades, que receberam tratamento estatístico, com separação em quartis e definição da mediana, para se chegar aos índices-padrão. Com isso, foi possível classificar os índices econômico-financeiros das cooperativas, em excelentes, bons, regulares e insatisfatórios, se comparados com o padrão setorial. O trabalho se justifica pela relevância dos indicadores-padrão como base de avaliação do desempenho econômico-financeiro tanto pelas cooperativas como pelo Sistema OCB/MS.

Determining the most accurate program for the Mann-Kendall method in detecting climate mutation

In the detection of abrupt changes in a time sequence using the Mann-Kendall method, two programs (PRGM1 and PRGM2) were found to provide two different mutation points for the same temperature sequence. The code of PRGM1 was programmed according to the step-by-step direction of the Mann-Kendall method described in the original report, and PRGM2 is the self-included program therein. To determine the reason for the different calculation results between the two programs for the same method and the same time series, and thereby verify the correctness of the programs, this study performed some analyses. First, the original reference, in which the basic principle of the Mann-Kendall method was put forward and developed, was reviewed to find the original mathematical formula of the Mann-Kendall method. Then, the mutation points calculated by PRGM1, PRGM2, and additional methods of detecting climate mutation were comparatively analyzed. The results show that the self-compiled program (i.e., PRGM1) and the self-included program (i.e., PRGM2) have different definitions of their main statistics when calculating the rank of a time series. Mutation points obtained by other methods were found to be consistent with those calculated by PRGM1 but different from those calculated by PRGM2. This proves that the definition of the main statistics for the rank of a sequence in PRGM1 is correct. Certain problems still exist in the definition of the main statistics for the rank of a sequence in PRGM2.

Reflection on modern methods: Statistics education beyond 'significance': novel plain English interpretations to deepen understanding of statistics and to steer away from misinterpretations.

Concerns have been expressed over standards of statistical interpretation. Results with P <0.05 are often referred to as 'significant' which, in plain English, implies important. This leads some people directly into the misconception that this provides proof that associations are clinically relevant. There are calls for statistics educators to respond to these concerns. This article provides novel plain English interpretations that are designed to deepen understanding. Experience teaching postgraduates at Imperial College is discussed. A key issue with focusing on 'significance' is the common inappropriate practice of implying no association exists, simply because P >0.05. Referring to strengths of association in 'study participants' gives them gravitas, which may help to avoid this. This contrasts with the common practice of focusing on imprecision, by referring to the 'sample' and to 'point estimates'. Unlike formal statistical definitions, interpretations developed and presented here are rooted in the application of statistics. They are based on one set of study participants (not many random samples). Precision of strengths of association are based on using strengths in study participants to estimate strengths of association in the population (from which participants were selected by probability random sampling). Reference to 'compatibility with study data, dependent on statistical modelling assumptions' reminds us of the importance of data quality and modelling assumptions. A straightforward graph shows the relationship between P-values and test statistics. This figure and associated interpretations were developed to illuminate the continuous nature of P-values. This is designed to discourage focus on whether P <0.05, and encourage interpretation of exact P-values.

1490-P: Disparities in Deaths Due to Diabetes, Diabetes Ketoacidosis, and Diabetic Coma by Urbanization among Children, Adolescents, and Young Adults: 1999-2017, United States

Although previous studies have reported higher diabetes (DM) mortality among individuals who live in rural areas, little is known about deaths due to DM, diabetic ketoacidosis (DKA) or diabetic coma by urbanization among U.S. population under age 45 years. We used National Vital Statistics System data from 1999 to 2017 filed in all 50 states and the District of Columbia obtained from CDC Wonder (wonder.cdc.gov). DM-related deaths were based on any listed ICD-10 codes E10-E14. DKA or diabetic coma deaths were based on any listed ICD-10 codes E10-E14 with X.1 or X.0. Urbanization was classified into 5 categories based on the 2013 National Center for Health Statistics definition. Results were reported for 1999- 2007, 2008-2017 and age standardized to the 2000 U.S. population by 10-year age groups for age 5 to 44 years. For both DM-related and DKA and diabetic coma deaths, rates for large fringe metro were lower than other areas (p &amp;lt; 0.001). (Table) The absolute difference in DM-related deaths increased over time in all urbanization categories (p &amp;lt; 0.05) except in large central metro. Rates of DKA or diabetic coma death increased significantly in medium/small and non-core areas (p &amp;lt; 0.05), but remained stable in large central metro. (Table) Exploring underlying causes for the disparities in deaths by urbanization may lead to improved care and fewer deaths. Disclosure S. Shaydah: None. G. Imperatore: None. C. Mercado: None. K.M. Bullard: None. S.R. Benoit: None.

Image-Based Cell Profiling Enables Quantitative Tissue Microscopy in Gastroenterology.

Immunofluorescence microscopy is an essential tool for tissue-based research, yet data reporting is almost always qualitative. Quantification of images, at the per-cell level, enables "flow cytometry-type" analyses with intact locational data but achieving this is complex. Gastrointestinal tissue, for example, is highly diverse: from mixed-cell epithelial layers through to discrete lymphoid patches. Moreover, different species (e.g., rat, mouse, and humans) and tissue preparations (paraffin/frozen) are all commonly studied. Here, using field-relevant examples, we develop open, user-friendly methodology that can encompass these variables to provide quantitative tissue microscopy for the field. Antibody-independent cell labeling approaches, compatible across preparation types and species, were optimized. Per-cell data were extracted from routine confocal micrographs, with semantic machine learning employed to tackle densely packed lymphoid tissues. Data analysis was achieved by flow cytometry-type analyses alongside visualization and statistical definition of cell locations, interactions and established microenvironments. First, quantification of Escherichia coli passage into human small bowel tissue, following Ussing chamber incubations exemplified objective quantification of rare events in the context of lumen-tissue crosstalk. Second, in rat jejenum, precise histological context revealed distinct populations of intraepithelial lymphocytes between and directly below enterocytes enabling quantification in context of total epithelial cell numbers. Finally, mouse mononuclear phagocyte-T cell interactions, cell expression and significant spatial cell congregations were mapped to shed light on cell-cell communication in lymphoid Peyer's patch. Accessible, quantitative tissue microscopy provides a new window-of-insight to diverse questions in gastroenterology. It can also help combat some of the data reproducibility crisis associated with antibody technologies and over-reliance on qualitative microscopy. © 2020 The Authors. Cytometry Part A published by Wiley Periodicals LLC. on behalf of International Society for Advancement of Cytometry.

P values and Ronald Fisher

The historic origins of the concept of P values are described together with its mathematical and statistical definition.

Emergence and Postoperative Atelectasis: Reply.

We appreciate Dr. Priebe’s interest in our article.1,2 The existence of outliers is an inherent feature of biology, and respiratory pathophysiology and atelectasis formation is certainly no exception to this rule. We can assure Dr. Priebe that all outliers were included in the analyses, which is also clearly stated in the Materials and Methods section. The statistical definition may vary, but according to the default setting in our statistical software, any observation that is 1.5 interquartile ranges below the first quartile or above the third quartile is deemed an outlier. In one of the boxplots in figure 2, no data point exists between the third quartile and 1.5 interquartile ranges, therefore no whisker is displayed. Furthermore, the nine outlier data points from eight patients are from two separate investigations, i.e., from a total data set of 60 observations. The proportion of outliers is therefore 13% and not 27%.The size of atelectasis is preferably discussed in terms of percentage of total lung area in a specific slice of the lungs. We insist that most patients had small atelectasis before awakening, with the median for all patients being only 1.3% of total lung area in a basal scan of the lungs,3 the most vulnerable parts. Indeed, five patients exhibited somewhat larger atelectasis: four of them still under 3% of total lung area and one with 4.1% of total lung area. These are not extreme numbers, but still statistically defined as outliers in our data, since nearly all other patients exhibited minimal atelectasis. Postoperatively, no single patient, outliers included, needed supplemental oxygen or had an oxygen saturation below 95%.Knowledge on the effect of awakening with Fio2 0.8 instead of 1.0 is still lacking. We would welcome evidence showing that awakening with Fio2 0.8 results in even smaller postoperative atelectasis, and we particularly look forward to the resulting discussion whether it is worth shortening safe apnea time by 25% to achieve this.4 Meanwhile, we prefer providing our patients with a maximum oxygen reserve during awakening.The authors declare no competing interests.

Optimal design of sport footwear with considering energy dissipation of lower limb soft-tissue during running

Summary Aims Postponing muscular fatigue and preventing injuries of the lower extremity during running are common desires for professional runners. These favorites may significantly be provided via reducing the energy dissipation (ED) at the lower limb soft-tissues (LLST). It is obvious that footwear plays a main role in this matter. Use of a pair of sport shoes made by materials having optimal viscoelastic parameters can certainly help to perform a professional running. Hence, in this paper we intend to find an optimal domain for the viscoelastic parameters of sport shoes, called safe area, at which the ED at the LLST is minimum. Methods Evaluation of the ED is done based on a mass-spring-damper (MSD) model, which provides a simulated signal of the vibrating movements of the human calf muscle during running. This model is primarily validated through experimental signals recorded from vibrations of the calf muscle of eight professional runners. Frequency characterization and comparison between the simulated and recorded signals asserts the accuracy of the model. Fast Fourier Transform (FFT) as well Continuous Wavelet Transform (CWT) techniques are utilized to this end. The ED estimation is obtained by two different methods; one is statistical definition of the signal average power, the other is calculation of mechanical dissipative work. Results Results show that the safe area of shoe-specific parameters obtained based on the ED criterion is a subdomain of the one obtained based on the physiological hypothesis relied on central nervous system (CNS) functionality, namely, constant ground reaction force (GRF) peaks and minimum amplitude of muscle vibrations.

Stochastic multiscale modeling of the thermomechanical behavior of polycrystalline shape memory alloys

A multi-scale model simulating hysteretic thermomechanical behavior of polycrystalline shape memory alloys (SMA) is presented. Using a kinetic Monte-Carlo approach, the energy-based model estimates the stochastic average in terms of volume fraction for a phase or phase variant deriving from the Gibbs free energy density as a selection inside a given population. Indeed pseudo-elastic behavior for example is well-known to be associated with the nucleation of martensite plates inside the austenite parent phase. Associated variants are similar to sub-domains inside a thermodynamic system following the statistical definition of Sommerfeld et al. (1964). The germination process of a variant is on the other hand dictated by a germination potential barrier identified from a differential scanning calorimetry (DSC) measurement. The stochastic average for each type of variants inside a grain leads then to the numerical simulation of hysteresis phenomena at the single crystal scale. Homogenization operations allow finally macroscopic quantities (phases fraction, deformation and temperature) to be calculated at the polycrystalline scale. This procedure is applied to model the whole thermomechanical behavior of an equiatomic Ni-Ti SMA polycrystalline alloy considering the phase transformation between austenite, R-phase and martensite.

Novel Second-Order Statistics of the Chirp Cyclostationary Signals

In communications and radar/sonar systems, one of the most popular nonstationary stochastic signal models is the chirp cyclostationary (CCS) signal. Recently, the second-order statistics of complex CCS signals are defined based on the conjugate correlation function, which have shown to be more proper in linear canonical transform domain than in the frequency domain. However, the information provided by unconjugate correlation function is missing, which leads to an incomplete study of second-order CCS signals. In this letter, the unified conjugate and unconjugate correlation function of CCS signals is researched. In detail, the definitions of the novel second-order statistics, chirp cyclic correlation and chirp cyclic spectrum, are expounded. Then the properties of these statistics are investigated. Finally, the additional information provided by the correlation function with conjugate operation and the usefulness of the proposed statistics are introduced and explained by simulations.

Quantification of tolerance limits of engineering system using uncertainty modeling for sustainable energy

Measurements always associate a certain degree of uncertainty. In order to achieve high precision measurement in presence of uncertainty an efficient computation is desired. Statistical definition of precision of any measurement is defined as one standard deviation divided by the square root of the sample size taken for measurements. Accordingly, tolerance limits are statistical in nature. Therefore, measurements are required to repeat large number of times to obtain better precision. Hence, the target is to establish the tolerance limits in presence of uncertainty in computer and communication systems. Nonparametric method is applied to establish the tolerance limits when uncertainty is present in measurements. The basic aim of the present paper is to explore order statistics based nonparametric method to estimate the appropriate number of samples required to generate the realizations of the uncertain random parameters which further will facilitate user to establish the tolerance limits. A case study of solute transport model is experimented where tolerance limits of solute concentration at any spatial location at any temporal moment is shown. Results obtained based on the nonparametric simulation are compared with the results obtained by executing traditional method of setting tolerance limits using Monte Carlo simulations using computer and communication systems.

Summary of Scientific and Statistical Methods, Study Endpoints and Definitions for Observational and Registry-Based Studies in Hematopoietic Cell Transplantation

Due to the increasingly strict word/character restrictions enforced by most scientific publications, we identified a need for a master document illustrating the “Scientific Methods” that may be applicable to the majority of observational and registry-based studies in hematopoietic cell transplantation (HCT). The purpose of this study is to serve as a reference document that describes the data source, study endpoints and statistical analyses utilized most commonly in retrospective studies in HCT. To this end we compile, define and reference the methodology commonly used in HCT research. While it is recognized that the scientific methodology may periodically require updates due to the evolving landscape of transplant research, such as newer study endpoints and statistical methods, this manuscript describes frequently used methodologies.

Mental health among immigrants in Germany \u2013 the impact of self-attribution and attribution by others as an immigrant

BackgroundIn Germany, the term ‘migration background’ has been established to differentiate between immigrants and natives. In the present study post-traumatic stress disorder (PTSD), anxiety, and depression were analysed in immigrant populations in Germany by considering self-attribution as well as attribution by others on one’s own ‘migration background’.MethodsIn a population-based survey (N = 2317), socio-demographic characteristics, migration background (official statistics definition vs. self-attribution as well as the anticipated attribution by others), PTSD (PCL-5), and symptoms of anxiety and depression (PHQ-4) were assessed. Logistic regression models were applied to predict mental health outcomes by considering socio-demographic and immigration-related factors.ResultsA total of 10.7% of respondents (N = 248) had a ‘migration background’. Immigrants of the 2nd generation compared to 1st generation immigrants are less likely to see themselves as immigrants. Attribution as an immigrant (self and/or by others) was found as significant predictor for PTSD and depression, but not anxiety.ConclusionsIt seems useful to focus on immigration-related factors considering subjective perspectives and not only comparing immigrants and natives using a federal statistics definition. Our findings suggest that research on the association between immigration-related factors such as attribution as an immigrant and mental health outcomes might be a promising approach to better identify subgroups at higher risk of mental distress.

Child care deserts in New York State: Prekindergarten implementation and community factors related to the capacity to care for infants and toddlers

Access to high quality child care provides a valuable support to families and communities as it both enables parental employment and provides a safe and developmentally appropriate place for children. Yet, access to child care for children under age three is uneven, with some communities experiencing child care “deserts” (Jessen-Howard et al., 2018). This paper assesses the infant and toddler child care capacity – the proportion of age-eligible children for which there are available child care slots – of communities across New York State. Using data from the NY State Education Department (670 school districts in the most recent year of available data), the NYS Office of Children and Family Services (about 18,000 registered child care providers), and the National Center for Education Statistics definitions of locale, we examine how child care capacity relates to school district and community factors over 9 years (2007–2016). Using negative binomial regression, we see overall stability in capacity for infant and toddler child care in New York State, but important variation by demographic factors and geography. Non-urban communities and communities with greater levels of student poverty have less capacity for infants and toddlers. Urban communities, communities with publicly funded prekindergarten and greater levels of minority children are associated with greater capacity. Importantly, in non-urban communities only (and especially in rural communities), we find an interaction effect that documents significantly reduced capacity for infant and toddler child care in communities also implementing public prekindergarten.

Republic of Madagascar

At the request of the Ministry of Finance and Budget (MFB) of Madagascar, and in consultation with the African Department of the International Monetary Fund (IMF), a technical assistance (TA) mission on government finance statistics (GFS) from the Statistics Department visited Antananarivo from March 4 to 15, 2019. The purpose of the mission was for the Malagasy authorities to adopt the Government Finance Statistics Manual (GFSM) 2014 concepts, definitions, and methodology as part of the macroeconomic statistics improvement project, namely the Enhanced Data Dissemination Initiative 2 (EDDI 2), financed by the Department for International Development (DFID); and Madagascar’s Strategic Plan to Modernize Government Finances (Programme Stratégique de Modernisation des Finances Publiques – PSMFP). This mission is also a continuation of previous TA missions on this topic (January and December 2016, and March 2018).

Statisticians as Back-office Policy-makers: Counting Asylum-Seekers and Refugees in Europe

Street-level bureaucracy literature ascertains that policies get made not only in the offices of legislatures or politicians but through the discretion bureaucrats employ in their day-to-day interactions with citizens in government agencies. The discretion bureaucrats use to grant access to public benefits or impose sanctions adds up to what the public ultimately experience as the government and its policies. This perspective, however, overlooks policy-making that gets done in the back offices of government, where there might not be direct interaction with citizens. Furthermore, it treats discretion as inherently anthropogenic and ignores that it is exercised in relation to sociotechnical arrangements of which bureaucrats are a part. In this paper, based on extensive ethnography at national statistical institutes and international statistical meetings across Europe, I make two arguments. The first is that, statisticians emerge as back-office policy-makers as they are compelled to take multiple methodological decisions when operationalizing abstract statistical guidelines and definitions, thus effectively making rather than merely implementing policies. This is the “discretion” they employ, even when they may not interact with citizens. The second argument is that the exercise of discretion is sociotechnical, that is, it happens in relation to the constraints and affordances of technologies and the decisions of other bureaucrats in their institutions and others.