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Hypothetical spatial patterns.
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This research is concerned with providing a generalized significance testing method for global measures of spatial association by extending the Mantel test. Even though it has long been recognized that univariate spatial association measures such as Moran's I and Geary's c are special cases of Mantel's generalized association statistic, an intensiv...
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Purpose:
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Methods:
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Citations
... Outbreaks. We used Global Moran's I index [24], Global Geary's C [46], and Global Getis-Ord Gi * [24] to analyze the spatial patterns in HPAI H5N1 outbreaks. A Moran's I value close to zero indicates a random distribution, while a negative Moran's I value indicates more dispersed H5N1 outbreak sites from random and positive values which indicate a clustering of H5N1 outbreaks. ...
Understanding disease clustering and transmission patterns improves the prevention and control of disease. Herein, we described the epizootic characteristics and spatiotemporal dynamics of High Pathogenicity Avian Influenza (HPAI) H5N1 outbreaks as well as clade diversity and phylodynamics of H5N1 over time and across host species in Bangladesh. We used Moran’s I, Geary’s C, Getis-Ord Gi∗, and a space-time permutation model to analyze the spatiotemporal patterns of H5N1 outbreaks. We used Bayesian phylogenetic analysis to generate a time-scaled maximum clade credibility (MCC) tree. Our study revealed nine HPAI H5N1 epizootic waves between 2007 and 2020 that invariably peaked in the wintertime. After vaccination of poultry against H5N1 was introduced in 2012, the incidence of HPAI H5N1 outbreaks and poultry mortality decreased significantly over time. Nonetheless, our research revealed that the virus continued circulating unabatedly in Bangladesh. The various spatiotemporal analyses were identified up to nine space-time clusters across Bangladesh, with the most significant clustering and hotspots of H5N1 outbreaks in and around the district of Dhaka. Since 2007, four H5N1 clades have been detected in Bangladesh, with only clade 2.3.2.1a continuing to circulate since 2011, which was followed up by the reassorted clade 2.3.2.1a in 2012. The HA gene of the H5N1 clade 2.3.2.1a has been reassorted into at least nine subgroups (R1–R9). After 2016, the first eight groups disappeared, with only the R9 group remaining. Spatiotemporal patterns and phylodynamics of H5N1 outbreaks are crucial for developing targeted and appropriate HPAI control and prevention measures. We recommended intensive monitoring of biosecurity measures and disease records in high-priority areas, along with assessing vaccine efficacy to better control HPAI outbreaks in Bangladesh.
... The grouping composition of body length and body weight among different habitats was analyzed by using a Chi-square test, and the post-hoc testing was employed [35,36]. The relationships between environmental factors and physical measurements of pill bugs were analyzed by using Cramer's V. Mantel test analysis [37]. The relationship between body length and body weight of pill bugs was derived by using regression analysis. ...
Simple Summary: Urban green areas are critically important for maintaining biodiversity in urban ecosystems. The pill bug is an ecological bio-indicator of soil health that is widely distributed around the world. In this study, we studied the relationship between the characteristics of the pill bugs population and soil properties of urban green spaces. The characteristics of the population vary significantly among selected habitats. The pH and soil organic matter may be the main factors for explaining the variation in body size of pill bugs among the habitats in spring. Significant positive regressions were detected between body length and body weight. Abstract: Rapid urban development poses a threat to global biodiversity. At the same time, urban green spaces offer opportunities for holding biodiversity in cities. Among biological communities, the soil fauna plays a crucial role in ecological processes but is often ignored. Understanding the effects of environmental factors on soil fauna is critical for ecological conservation in urban areas. In this study, five typical green space habitats were selected including bamboo grove, forest, garden, grassland, and wasteland in spring, for detecting the relationship between habitats and Armadillidium vulgare population characteristics in Yancheng, China. Results indicate that soil water content, pH, soil organic matter, and soil total carbon varied significantly among habitats, as well as the body length and body weight of pill bugs. The higher proportion of larger pill bugs was found in the wasteland and the lower proportion in the grassland and the bamboo grove. The body length of pill bugs was positively related to pH. Soil total carbon, soil organic matter, and the number of plant species were correlated with the body weight of pill bugs.
... is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint (40)(41)(42). This is a global bivariate spatial correlation test, which integrates an aspatial bivariate measure (Pearson's correlation) and a univariate spatial measure (Moran's I). ...
Background
The genetic and environmental aetiology of autistic and Attention Deficit Hyperactivity Disorder (ADHD) traits is known to vary spatially, but does this translate into variation in the association of specific common genetic variants?
Methods
We mapped associations between polygenic scores for autism and ADHD and their respective traits in the Avon Longitudinal Study of Parents and Children (N=4,255 to 6,165) across the area surrounding Bristol, UK, and compared them to maps of environments associated with the prevalence of autism and ADHD.
Results
Our maps suggest genetic associations vary spatially, with consistent patterns for autistic traits across polygenic scores constructed at different p-value thresholds. Patterns for ADHD traits were more variable across thresholds. We found that the spatial distributions often correlated with known environmental influences.
Conclusions
These findings shed light on the factors that contribute to the complex interplay between the environment and genetic influences in autism and ADHD traits.
Key points
The prevalence of autism and ADHD vary spatially.
Our study highlights that genetic influences based on PGS also vary spatially.
This spatial variation correlates with spatial variation in environmental characteristics as well, which would be interesting to examine further.
Our findings have implications for future research in this area examining the factors that contribute to the complex interplay between the environment and genetic influences on autistic and ADHD traits.
... We used the bivariate association measure L (Lee 2001(Lee , 2004 to parameterise the spatial dependence and to test the similarity of the spatial patterns of the shading effects. For the pairwise tests, taking N as reference (control trees against pruned structures), subset-ground-areas of 336 m 2 (24 m 9 14 m) were used, encompassing the core area of the annual insolation reduction on the ground, from the tree trunk 4 m to the south, 10 m to the north, and 12 m towards west and east directions. ...
Light is a limiting resource for crops within integrated land use systems especially those including woody perennials. The amount of available light at ground level can be modified by artificially pruning the overstory. Aiming to increase the understanding of light management strategies, we simulated the pruning of wild cherry trees and compared the shading effects of the resulting tree structures over a complete growing season, with fine spatiotemporal resolution. Original 3D-tree structures were retrieved employing terrestrial laser scanning and quantitative structure models, and subjected to two pruning treatments at low and high intensities. By using the ‘shadow model’, the analogous tree structures created diverse shaded scenarios varying in size and intensity of insolation reduction. Conventional pruning treatments reduced the crown structure to the uppermost portion of the tree bole, reducing the shading effects, and thus, shrinking the shaded area on the ground by up to 38%, together with the shading intensity. As an alternative, the selective removal of branches reduced the shading effects, while keeping a more similar spatial distribution compared to the unpruned tree. Hence, the virtual pruning of tree structures can support designing and selecting adequate tending operations for the management of light distribution in agroforestry systems. The evidence assembled in this study is highly relevant for agroecosystems and can be strategically used for maintaining, planning and designing integrated tree-crop agricultural systems.
... The categorical traits were extracted from "Fishes in Fujian Province" and FishBase. & Kot, 1990), while Lee's L test was used to detect bivariate spatial autocorrelation between them (Lee, 2004 ...
• Freshwater biodiversity is currently under multiple threats. Conservation of freshwater fish biodiversity needs to be prioritized because natural conservation resources are always limited.
• Samples were collected at 24 sites in the Min River, the largest basin in southeastern China. Taxonomic, functional, and phylogenetic diversity were analyzed. Biodiversity vulnerability was measured by removing one species each time out of the community with replacement.
• Results suggested that hotspots for taxonomic and phylogenetic diversity were located at two impounded sites, while for functional diversity were those sites with no upstream dams. Little congruence was observed between taxonomic, functional, and phylogenetic diversity. Fragmentation of river network connectivity caused by dams was a significant factor affecting the biodiversity patterns. Beta turnover was the driving component for beta diversity, indicating that biodiversity dissimilarity along the river was mostly explained by environmental sorting. Fifteen out of 16 species that contributed the most to different facets of biodiversity were mostly endemic, either they had distinctive functional traits or they were the most prevalent species. Sites with the highest diversity vulnerability were characterized by these distinctive species. Functional diversity was more vulnerable to species loss comparing with the other two biodiversity facets.
• Prioritizing those biodiversity hotspots, sites with extreme functional vulnerability, and those distinctive endemic species which contributed the most to biodiversity vulnerability is suggested in the Min River. The study found evidence that congruence among different facets of biodiversity is hard to achieve, and functional diversity is the most vulnerable in a freshwater system fragmented by intensive dam constructions. This work will help to develop systematic conservation planning from the perspective of different biodiversity facets.
... As Openshaw (1984) points out, the zoning effect may be greater than the scale effect. Lee (2001) proposes a spatial smoothing scale, which is subsequently named S, as an alternative univariate SA measure (Lee 2004(Lee , 2009(Lee , 2017. This particular measure is based on the concept that the SA level of a geographic variable is directly associated with the amount of variance reduction attributable to transforming a variable to a spatial lag vector or a spatial moving average vector. ...
... Second, the initial level of bivariate SA also may have a considerable impact on the variability of MAUP effects. This task may require a proper measure for the level of bivariate SA among possible options, including bivariate MC and Lee's L statistics (Lee 2001(Lee , 2004, particularly L* (Lee 2017). In addition, a much more complicated simulation framework is needed to employ both the initial level of correlation and the initial level of bivariate SA, which is beyond the scope of this research. ...
... Several global SA measures have been widely used to measure the magnitude of SA in the entire study area. Examples include Moran's I (MC) and Geary ratio (GR), G-statistic, and Lee's S (Lee 2004). To evaluate the SA in each subunit within a region, local indicators of spatial association (LISA; i.e., local MC and local GR; Anselin 1995), G i (and G i à ), and local spatial heteroskedasticity measures (Ord and Getis 2012) have been developed. ...
... The global SBC as well as MC and GR (Anselin 1995;Lee 2004;Wong 2011) are special cases of the Mantel statistic (Mantel 1967), which is defined as follows: ...
... where W is a spatial weights matrix and 1 is an n  1 vector of ones. Because the global SBC is formulated in the form of the Mantel statistic, its expected value and the variance can be derived with the Mantel's finite approach (Mantel 1967), which is the same as the randomization approach in statistical hypothesis tests in the traditional SA measures (Lee 2004). The detail formulations for the expected value and variance of the global SBC were based on Lee (2004Lee ( , 1691. ...
Local spatial autocorrelation (SA) measures have been used in exploratory spatial data analysis, particularly in detecting spatial clusters. Existing local SA measures, however, are likely unreliable and biased because they compare only estimates among neighboring spatial units, ignoring errors associated with these estimates. The spatial Bhattacharyya coefficient (SBC) compares probability distributions by considering both estimates and their standard errors. Therefore, it was proposed to be a global SA measure. This article argues that the local version of SBC can serve as a local SA statistic, addressing the deficiency of existing local SA statistics that fail to consider estimate error in their formulations. Significance tests for local SBC are conducted under conditional and total randomization assumptions by using a generalized randomization approach. Simulation experiments and empirical analyses of American Community Survey data show that local SBC complements traditional local SA measures by incorporating data reliability information of estimates in SA assessment. This study shows that the direct comparison of estimate distributions in neighboring units in local SBC is more similar to the comparison of neighboring estimates in local Geary than to the comparison of mean deviations in local Moran. Thus, local SBC can effectively detect zonal boundaries.
... In order to parameterise the bivariate spatial dependence, and to test the similarity of the spatial patterns of the shading effects, we calculated the bivariate association measure L [60,61]. For these spatial analyses, we used a subset data corresponding to a grid area of 128 m 2 (rectangle of 16 m × 8 m), encompassing the majority of the insolation reduction on ground, from the tree trunk 2 m to the south, 6 m to the north, and 8 m towards west and east directions. ...
Reduced solar radiation brought about by trees on agricultural land can both positively and negatively affect crop growth. For a better understanding of this issue, we aim for an improved simulation of the shade cast by trees in agroforestry systems and a precise estimation of insolation reduction. We present a leaf creation algorithm to generate realistic leaves to be placed upon quantitative structure models (QSMs) of real trees. Further, we couple it with an enhanced approach of a 3D model capable of quantifying shading effects of a tree, at a high temporal and spatial resolution. Hence, 3D data derived from wild cherry trees (Prunus avium L.) generated by terrestrial laser scanner technology formed a basis for the tree reconstruction, and served as leaf-off mode. Two leaf-on modes were simulated: realistic leaves, fed with leaf data from wild cherry trees; and ellipsoidal leaves, having ellipsoids as leaf-replacement. For comparison, we assessed the shading effects using hemispherical photography as an alternative method. Results showed that insolation reduction was higher using realistic leaves, and that the shaded area was greater in size than with the ellipsoidal leaves or leaf-off conditions. All shading effects were similarly distributed on the ground, with the exception of those derived through hemispherical photography, which were greater in size, but with less insolation reduction than realistic leaves. The main achievements of this study are: the enhancement of the leaf-on mode for QSMs with realistic leaves, the updates of the shadow model, and the comparison of shading effects. We provide evidence that the inclusion of realistic leaves with precise 3D data might be fundamental to accurately model the shading effects of trees.
... The verification of a possible pattern of association between two georeferenced variables can be measured by measures of global bivariate autocorrelation, such as the bivariate Moran index and the L statistic (Lee, 2001;Lee, 2004). The purpose of these measurements is to show whether the values of one variable observed in one region reveal a relationship with the values of another variable observed in neighboring regions. ...
In this work, the aim was to evaluate the existence of spatial association of the municipal average official soybean yield (t ha-1) with agrometeorological data and vegetation indices. The information was observed by ten-day periods, in crop years 2010/2011, 2011/2012 and 2012/2013 in the State of Paraná. Local univariate spatial correlation (LISA index), as well as global bivariate correlation (L statistics) were calculated. With this study, we identified neighboring municipalities with high yield in the West as well as municipalities that are located with low-low yield Northwestern, showing positive spatial autocorrelation (IMG=1), significative (p-value < 0.05). In addition, there were differences between seeding times in different regions, and climate irregularity during flowering periods and grain filling in crop year 2011/2012 throughout the state, which caused a large drop in production in all municipalities of the state of Paraná. The analysis of local spatial association showed that in the three crop years, the Northwest region presented a significant low yield potential of soybean (p-value < 0.05). In addition, it was observed that the period from the 3rd ten-day period of October to the 2nd ten-day period of January was essential for the soybean cycle in the different regions of the state, since this period encompasses the critical phases of crop. Differences were also observed between the crop years studied, regarding the agrometeorological variables, which affected soybean yield mainly in the Western region of Paraná – Brazil.
... Eq. 3 is often referred to as Lee's S and can be used to measure univariate spatial autocorrelation just like Univariate Moran's I (Lee, 2004). In spite of the criticism of the ideas of Wartenberg (1985), the approach has remained popular, with Anselin et al. (2002) expanding the formulation to visual analysis of bivariate Moran's I spatial association measure. ...
... Research has shown that 99 permutations should suffice when testing at 5% significance level. Lee (2004) provided a framework for significance testing of indicators of spatial association measures. In this framework an indicator of spatial association measure, sayΓ(obs), was determined for the deaths due to the three cardiovascular conditions. ...
South Africa is experiencing an increasing burden of noncommunicable diseases (NCDs). There is evidence of co-morbidity of several NCDs at small geographical areas in the country. However, the extent to which this applies to joint spatial autocorrections of NCDs is not known. The objective of this study was to derive and quantify multivariate spatial autocorrections for NCDrelated mortality in South Africa. The study used mortality attributable to cerebrovascular, ischaemic heart failure and hypertension captured by the country’s Department of Home Affairs for the years 2001, 2007 and 2011. Both univariate and pairwise spatial clustering measures were derived using observed, empirical Bayes smoothed and age-adjusted standardised mortality rates. Cerebrovascular and ischaemic heart co-clustering was significant for the years 2001 and 2011. Cerebrovascular and hypertension co-clustering was significant for the years 2007 and 2011, while hypertension and ischaemic heart co-clustering was significant for the year 2011. Co-clusters of cerebrovascular-ischaemic heart disease are the most profound and located in the south-western part of the country. It was successfully demonstrated that bivariate spatial autocorrelations can be derived for spatially dependent mortality rates as exemplified by mortality rates attributed to three cardiovascular conditions. The identified co-clusters of spatially dependent health outcomes may be targeted for an integrated intervention and monitoring programme.
