heterogeneity of variance
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2021 ◽  
Vol 8 (5) ◽  
pp. 487-499
Author(s):  
Bryce Mulligan ◽  
Stanley Koren

Formal scientific study of the geopsychology of human aggression dates back at least a century and has consistently demonstrated a positive association between solar-geomagnetic activity and aggressive behaviour. Advances in the theories, methodologies, and practical applications of geopsychology could therefore contribute to collective efforts to comprehend, to forecast, and to develop interventions for aggressive behaviours such as those seen in terrorism. This requires a rigorous and precise estimate of the magnitude of association between solar-geomagnetic activity and aggression using a representative, contemporary sample of strictly-operationalized behaviour. Here we show that days in recent history (1970-2018) with the lowest levels of instrumental human aggression (number of casualty-associated terrorism incidents) also had the lowest levels of solar and geomagnetic activity, and that stepwise increases in human aggression were mirrored by progressive increases in solar activity. We used Bayesian methods robust to outliers and heterogeneity of variance to analyze the most comprehensive and contemporary global database of terrorism incidents available, which included more than 106,000 unique instances of instrumental aggression spanning 48 years. We conclude that there is a small, nonzero promotional effect of solar-geomagnetic activity on terrorism-related aggression. This may reflect the fact that solar-geomagnetic activity serves as a zeitgeber that coordinates the expression of instrumental aggression across an aggregation of susceptible individuals. We propose that many behaviours – even instrumental acts such as terrorism which are presumed to involve a degree of planning and intention – may be subject to subtle geopsychological induction or suppression.


Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Juan F Toscano ◽  
Hao Jiang ◽  
Miguel Quintero-Consuegra ◽  
Nestor R Gonzalez

Introduction: Some publications have shown encephalomyosinangiosis (EMAS) as a potential model for surgical indirect revascularizations (SIR). Despite these reports, the validity of this model for neovascularization has not been addressed, in particular the observed variability in vessel proliferation response to ischemia and spontaneous neovascularization. Therefore, we present a systematic quantitative approach to evaluate the validity and variability of EMAS as a SIR model. Methods: We induced precise cerebral ischemia by ligation of the distal MCA via a 3mm temporal craniotomy on C57/BL6J mice. Subjects were randomly allocated to EMAS (placement of temporalis muscle in direct apposition to the brain) or controls (placement of an inert barrier-Teflon). After surgery, animals received BrdU in drinking water to mark newly formed cells. Brain tissue was harvested 14 days after surgery and stained with CD31, NeuN, anti-BrdU-Ab, and DAPI. New-vessels were defined as BrdU/CD31 co-staining, neuronal survival was quantified with NeuN density percentage. Groups were compared using regression mixed models and variability was evaluated using the heterogeneity of variance (HOV) test. Results: New-vessels were seen in the control and EMAS groups. The mean number of new vessels was 8 (SD 4.4) in controls vs. 15.8 (SD 5.1) in EMAS. The effect of treatment (EMAS vs. control) was a significant predictor of new-vessel formation (p<0.01, OR = 1.5 (95% CI: 1.1 - 1.9). The HOV between groups was non-significant. However, CD31 staining alone was not different (controls = 0.58 vs EMAS = 0.59). In terms of neuronal survival, the median NeuN density percentage distribution was 0.9% (IQR=1.2) for controls and 1.6% (IQR= 0.8) for EMAS (p = 0.2). The HOV was also non-significant. Conclusion: EMAS is a suitable model for evaluation of neovascularization after ischemic stroke. However, isolated quantifications of endothelial markers, such as CD31, are insufficient. The use of BrdU, which incorporates in newly synthesized DNA, in combination with endothelial markers is essential to quantify neovascularization. Neovascularization requires time and, as shown in this model, have little impact in neuronal survival in acute stroke.


2020 ◽  
Vol 2 (1) ◽  
pp. 19-28
Author(s):  
Salsabila Hasiana Tanjung ◽  
Suparno Suparno

The experimental design in this study has a particular interest in making conclusions made about gender differences in the ability to analyze children aged 5 years in the perspective of Taxonomic Bloom. The problem in this research is represented by the sample of research subjects by using items that have been loaded instrument. Test reliability and heterogeneity of variance can be randomly drawn conclusions from the scores of women and men on the instrument used. The results showed a statistically significant effect size difference difference (.01 Mean) in favor of women. The magnitude of gender differences in the impact of learning outcomes, however, differs substantially throughout the specific product domain graphically.


2018 ◽  
Vol 36 (3) ◽  
pp. 382-388
Author(s):  
Alessandro D Lúcio ◽  
Daniel Santos

ABSTRACT This work aimed at studying the variability of production of snapbeans grown in plastic greenhouses and the effectiveness of experimental borders and plot size in reducing such variability. Data from a uniformity experiment carried out in a plastic greenhouse were used. The analyzes were performed over spatial arrangements that considered the plants first arranged in planting rows parallel to the lateral openings of the greenhouse and then arranged in columns, perpendicular to these openings. Different scenarios were produced by excluding rows and columns. The homogeneity of variances between the remaining rows and columns was tested in each scenario, and the variance and the coefficient of variation were calculated as well. There was heterogeneity of variance between rows in the experiment. Borders were not effective in reducing the coefficient of variation or the frequency of cases of heterogeneity of variances between rows. Plots with two or more plants provided homogeneity of variances between rows and columns, creating room for the possibility of using the completely randomized design in experiments with snapbeans in plastic greenhouses.


2018 ◽  
Vol 213 ◽  
pp. 54-60
Author(s):  
Nadia Guzzo ◽  
Cristina Sartori ◽  
Roberto Mantovani

2018 ◽  
Vol 37 (5) ◽  
pp. 649-668 ◽  
Author(s):  
Arne Weigold ◽  
Ingrid K. Weigold ◽  
Sara N. Natera

The increasing number of self-report surveys being collected using computers has led to a body of literature examining the response rates for computerized surveys compared with the more traditional paper-and-pencil method. However, results from individual studies have been inconsistent, and the meta-analyses available on this topic have included studies from a restricted range of years and did not use proper statistical procedures for examining comparability. Consequently, we conducted a meta-analysis with 96 independent effect sizes spanning over two decades of studies; we also assessed potential moderators. Comparability was determined using confidence interval equivalence testing procedures. The meta-analysis indicated nonequivalence, with those in the paper-and-pencil condition being almost twice as likely to return surveys as those in the computer condition. There was large heterogeneity of variance, and 11 of the 18 potential moderators were significant. Two meta-regressions yielded only two significant unique moderators: population and type of measure. Results highlighted issues within the response rate literature that can be addressed in future studies, as well as provided an example of using equivalence testing in meta-analyses.


Irriga ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 140
Author(s):  
Adriele Aparecida Pereira ◽  
Tales Jesus Fernandes ◽  
Myriane Stella Scalco ◽  
Augusto Ramalho De Morais

MODELAGEM NÃO LINEAR DO CRESCIMENTO EM ALTURA DO CAFEEIRO IRRIGADO E NÃO IRRIGADO EM DIFERENTES DENSIDADES  ADRIELE APARECIDA PEREIRA1; TALES JESUS FERNANDES2; MYRIANE STELLA SCALCO3 E AUGUSTO RAMALHO DE MORAIS4 1Licenciada em Matemática, Mestre, DEX/UFLA, Lavras-MG, e-mail: [email protected] em Matemática, Doutor, Prof. DEX/UFLA, Lavras-MG, e-mail: [email protected] Agrônoma, Doutora, DAG/UFLA, Lavras-MG, e-mail: [email protected] Agrônomo, Doutor, Prof. DEX/UFLA, Lavras-MG, e-mail: [email protected]  1 RESUMO Heterogeneidade de variâncias e autocorrelação residual são características inerentes à dados de crescimento ao longo do tempo que se não considerados nas análises podem conduzir a resultados imprecisos. Este estudo teve por objetivo comparar os ajustes dos modelos Logístico e Gompertz, considerando os métodos de mínimos quadrados: ordinários e generalizados. Os dados utilizados referem-se à altura de plantas do cafeeiro, submetidas aos regimes de irrigação Si (testemunha), 60 kPa e 140 kPa, nas densidades de plantio 2500 e 5000 plantas ha-1. Segundo o desvio padrão residual e a análise de resíduos, o ajuste do modelo Gompertz pelo método de mínimos quadrados generalizados, que incorpora a heterogeneidade de variâncias e autocorrelação residual na modelagem, apresentou os melhores resultados para todos os dados analisados, sendo indicado para modelar o crescimento em altura do cafeeiro ao longo do tempo. Os ajustes referentes às plantas irrigadas apresentaram as maiores estimativas para a altura assintótica, confirmando que a irrigação da lavoura proporciona maior crescimento das plantas. Palavras-Chave: Autocorrelação residual, Gompertz, Heterocedasticidade.  PEREIRA, A. A.; FERNANDES, T. J.; SCALCO, M. S.; MORAIS, A. R. de MODELING NONLINEAR GROWTH IN HEIGHT COFFEE WITH AND WITHOUT IRRIGATION IN DIFFERENT DENSITIES  2 ABSTRACT Heterogeneity of variance and residual autocorrelation characteristics are inherent in the growth data over time that is not considered in the analysis may lead to inaccurate results. This study aimed to compare the settings of the Logistic and Gompertz models, considering the methods of least squares: ordinary and generalized. The data used refer to the height of the coffee plants, subjected to irrigation systems Si (non irrigated), 60 kPa and 140 kPa, the planting densities in 2500 and 5000 plants ha-1. According to the residual standard deviation and the residual analysis, the fit of the Gompertz model by generalized least squares method, which incorporates the heterogeneity of residual variance and autocorrelation in modeling, showed the best results for all data analyzed, suitable for modeling the growth in height of the coffee over time. The adjustments related to the irrigated plants had the highest estimates for the asymptotic height, confirming that the crop irrigation provides greater plant growth. Keywords: Residual autocorrelation, Gompertz, Heteroscedasticity.


2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e12085-e12085
Author(s):  
Norman R. Williams

e12085 Background: Breast cancer is an increasingly treatable disease which means that many women will live a long time with the esthetic consequences of their treatment. The majority of women with early breast cancer are given whole breast external beam radiation therapy (EBRT) after lumpectomy (breast conservation). It has been demonstrated, using an objective assessment of esthetic outcome in patients from a randomized trial that “redness”, a surrogate for radiation induced erythema grade I or II, is significantly greater after one year in patients receiving EBRT compared with those receiving intraoperative radiation therapy (IORT). However, it has been observed that not all women given EBRT have detectable erythema, which implies that there is a greater variability in this group. In order to test this hypothesis a test of unequal group variances was performed. Methods: 991 frontal digital photographs were analyzed from women participating in the TARGIT A Trial (NCT00983684) at four sites (Lublin, Mannheim, Copenhagen and Perth). Photographs taken at baseline (before surgery), 1 and 2 years (after surgery and EBRT or IORT) were objectively assessed, blinded to treatment received, by BCCT.core software which produces overall Harris scores, and scores for various measures of symmetry, color and scar. The scores for color were analyzed in SAS v9.4 using PROC GLM. Results: cEMDL, a color score associated with "lightness", showed significant heterogeneity of variance (using Levene's and Welch's Tests, p < 0.0001) in the women treated with EBRT, but not in those treated with IORT (p = 0.4). However, cX2b (associated with "redness") showed significant heterogeneity of variance in both the EBRT and IORT treated groups (p < 0.0001), although the point estimates moved in different directions. Conclusions: This study demonstrates that there are complex changes in skin color following radiation therapy to the breast, and assumptions regarding homogeneity of variance should be checked if required by the statistical analysis.


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