spatial correlation

In some instances, the occurrence of an event can be influenced by its spatial location, giving rise to spatial survival data. The accurate and precise estimation of parameters in a spatial survival model poses a challenge due to the complexity of the likelihood function, highlighting the significance of employing a Bayesian approach in survival analysis. In a Bayesian spatial survival model, the spatial correlation between event times is elucidated using a geostatistical model. This article presents a simulation study to estimate the parameters of classical and spatial survival models, evaluating the performance of each model in fitting simulated survival data. Ultimately, it is demonstrated that the spatial survival model exhibits superior efficacy in analyzing blood cancer data compared to conventional models.

In this research, the spatial correlation between the variables representing Bouguer gravity anomaly and seismicity in Iran is evaluated. For this purpose, the gravity anomalies and seismicity data of this region have been analyzed statistically as well as geostatistically, for the period 1975-2021. Based on the findings of this study, it can be concluded that the significant correlation observed between the variables of gravity anomaly variations and the seismicity-related variables, especially the variables related to the frequency of earthquake occurrences, suggests that the gravity anomaly variations can be considered as an affective factor in seismic activity of this region.The Iranian Plateau is one of the most seismically active regions on the Earth because of its geologic and tectonic setting. This plateau is marked by high topography relief and also by great changes in gravitational and isostatic anomalies across it. Many researchers have studied the variations of gravitational anomalies across Iran, and some have pointed to the relationships between these anomalies and seismicity in this region. The Bouguer gravity anomaly is obtained by making the necessary corrections to measurements taken directly from the ground stations, and well reflects the deep density variations in the crust. This anomaly can also clearly show changes in crustal thickness in different regions, such that areas with high crustal thicknesses show negative anomalies and areas with low crustal thicknesses show positive anomalies.In this study, at first, the study region was divided into rectangles with dimensions of 0.5 by 0.5 geographical degrees and then the variables related to the seismicity and gravity anomalies were calculated and computed for each cell. Pearson correlation coefficients between these variables were computed and validated using statistical software Minitab (ver. 16.2.2). Also, maps representing the spatial distribution pattern of these variables were prepared. The remarkable similarity between the spatial patterns of variations of these variables indicates a strong correlation between the Bouguer gravity anomaly and seismicity in this region. The Pearson correlation coefficient values calculated between the variables also confirm this correlation. These values indicate that both variables of average Bouguer anomaly and the range of variations of this anomaly show a significant positive correlation with the seismicity-related variables. This degree of correlation is stronger for the variable of the Bouguer anomaly variation and moreover, this variable is more correlated with the seismicity variables associated with the frequency of earthquakes. In the next step, variograms were prepared.     The results obtained show that among the seismicity-related variables of the region, the b seismicity parameter (from the Gutenberg-Richter relation) has more spatial variability and show high spatial autocorrelation up to long distances. On the other hand, the other variables related to earthquake frequency and magnitude of earthquakes show less spatial autocorrelation. The variograms provided for the two variables representing the bouguer anomaly also show remarkable similarity to the seismicity-related diagrams. This similarity is more pronounced for the variable of the Bouguer anomaly variation. The remarkable similarities of the variograms, along with the similarities of the spatial distribution maps of these variables, may indicate a close relationship between these two series of variables. Finally, it can be concluded that gravitational forces, especially forces caused by isostatic imbalances, can play an important role in the process of earthquake occurrences in Iran.

Changes in the quality of underground resources for various reasons, especially the unconventional use of these resources can have devastating effects on the environment.In this research, groundwater quality parameters including electrical conductivity, total soluble solids, acidity, sodium adsorption ratio, hardness, bicarbonate, chloride, sulfate, calcium, magnesium, sodium, potassium, and the sum of anions and cations were used. in this research, groundwater quality data related to piezometric water wells affiliated to the Hamadan Regional Water Company for four-year periods in 2009, 2013, 2017, and 2020 in the plains of Hamadan province have been used. The results of Moran and coefficient of gery show that the spatial distribution pattern of all water quality parameters in 2009 and 2020 is random and for the parameters of electrical conductivity and sodium adsorption ratio in 1992 and 1996, respectively, with a high level of confidence of 95% and 90%, respectively, it had a spatial distribution with a cluster pattern with high values. To investigate the spatial variations of electrical conductivity using the Kriging method, water quality maps in terms of electrical conductivity parameters for the years 2009, 2013, 2017, and 2020 have been prepared. The map of electrical conductivity changes prepared from 2009 to 2020 years shows that the amount of electrical conductivity in the city of Hamedan (Qahvand) and Razan and Kaboudar Ahang plains has more increasing changes, which indicates a decrease in groundwater quality in the case study area. Therefore, planning is necessary to correct the decline in groundwater quality.

Valuing ecosystem services requires consideration of spatial patterns. Therefore, we used new spatial statistics methods, such as Moran's spatial correlation and GIS capability, to identify and determine spatial patterns of ecosystem services after quantifying habitat ecosystem services in the Qarah Qeshlaq wetland, a 22,000 ha wetland between the eastern and western Azerbaijan provinces. Studies show that there are 13 types of land uses in the area of Qarah Gheshlagh wetland, which in the area of about 22,000 hectares shows the diversity of land use and in fact the active presence of human factors, about 46% of the area has agricultural land and about 28% of saline land. In this regard, residential centers as a threat center and access road as a threat development have been the largest share in land use change. According to the Moran index of 0.62 and the expected index of -0.000017 and the z-score of 1505869, the probability of random distribution is low and the distribution is clustered. The optimized analysis of the sensitive points in the area of Qarah Qeshlaq wetland reveals that the correlation is highest on the western side of the wetland where there is no human activity, while it is lowest on the eastern side where there is a great deal of human activity.IntroductionIn general, any type of wetland is composed of a large number of physical, biological or chemical factors, and water, soil and nutrients represent these components that, in conjunction with each other in an integrated system, form the wetland and the processes between the components, the functions of the components. Creates. Wetlands are defined based on their biological, chemical, and physical properties, regardless of their specific function, production, or process (Ganagey, 2018). In order to identify wetlands, first the type of wetlands must be determined from a hydrological point of view, and each of the different classes of wetlands provides different ecosystem services. In other words, many benefits that ecosystems provide to individuals are called ecosystem services.Methodology Introduction of the study areaThe study area of Qaraghshlagh wetland with an area of 22,000 hectares is located between East Azerbaijan and West Azerbaijan provinces and on the outskirts of Bonab and Miandoab cities in a geographical position of 37 degrees 13 minutes and 25 seconds north latitude and 45 degrees and 51 minutes and 38 seconds east longitude. It is located on the south shore of Lake Urmia at an altitude of 1270 meters above sea level.InVEST habitat quality model, by combining land use / vegetation patterns and biodiversity threats, leads to the production of habitat quality maps. This model is implemented using raster data or maps divided into square cells (pixels). Each pixel in the image is assigned to a type of land use / vegetation, which can be a natural cover or a man-made cover. This approach provides two basic types of information necessary for the initial assessment of conservation needs: which includes the relative extent and extent of degradation of different types of habitats in an area and its various changes over time.Understanding patterns and discovering trends in spatial data is important. Because before any analysis, it must be determined how the data are distributed in space and their spatial patterns. In this study, Moran correlation statistic was used to analyze the spatial correlation of ecosystem services. There are two types of Moran indices to determine the spatial correlation between variables whose efficiency is different from each other. Global Moran Index and Local Moran Index. One of the most basic global indicators of solidarity is the Moran index. This index gives a number (as a standard score) that can be used to measure the dispersion or concentration of phenomena or spatial data.ResultsLand use related to the current timeThere are 13 types of land uses in the area of Ghareh Gheshlagh wetland, which in the area of about 22,000 hectares shows the diversity of land use and in fact the active presence of human factors, about 46% of the area has agricultural land and about 28% is saline land. If this area was not saline, it could be added to the area of agricultural land. Of the remaining 24%, about 7% is used as a fish farm and 7% is a rangeland. In other words, 35% of the lands in this area are national lands (rangeland and saline). Only 10% of the area as an aquatic habitat belongs to Qarah Gheshlagh wetland, river, flood area and water supply canal. Qarah Gheshlagh wetland in the current situation with an area of about 140 hectares and covers less than one percent of the area (Figure 2). In evaluating ecosystem services, there is a wider range of goals, including ecological sustainability and social welfare, along with the traditional economic goal of efficiency. In fact, by determining the value of ecosystem services in socio-economic and ecological dimensions, we can understand the contribution of each of these services in achieving the above goals. Therefore, due to the heterogeneity of units of measurement in three dimensions of economic, social and ecological, it is necessary to develop criteria for measuring each and in some cases to determine the degree of importance of these criteria in the specific service of the ecosystem by qualitative weighting. On the other hand, the implementation of the development plan can have different socio-economic and ecological effects; Effects that can change the value of ecosystem services and reduce and in some cases increase the value of these services.In the present study, in order to investigate the spatial structure of ecosystem services in the area of Gharaghshlagh wetland, spatial statistics (value2 column of land use) have been evaluated. The statistics used, based on the conceptualization of the dispersion index, examine the ratio of variance to the average based on the distance of services. 0.62 does not follow a random distribution, but the p-value is zero, which indicates a high correlation and cluster distribution and is significant.According to Table 4, the Moran index is 0.62 and the expected index is negative 0.000017 and the z-score is 1505869. The probability of random distribution is low and is in the form of clusters. Examination of Map 5 Analysis of hotspots in Qarah Gheshlagh area shows the southwest side of the area which includes wetland, fish breeding place, Zarrineh river and flood spreading place in this area has the highest value and in the eastern side of the area which is agricultural use has the lowest value or points. It is hot or correlated, and there is no correlation with pale pink in the center of the range and paths of rivers and water supply canals.ConclusionQarah Gheshlagh wetland is located on the shores of Lake Urmia and at the mouth of large rivers such as Zarrineh and Simaneh rivers, as well as Mordagh Chai, Leylan Chai and Sufi Chai, and has been a habitat and water source in the region. These wetlands have provided food, drinking water, pastures and transportation routes for indigenous communities and have emerged as part of their culture. In this study, the spatial correlation pattern for habitat ecosystem service was investigated. Gharaghshlagh wetland is the first station for waterfowl in the country due to its migration route from north to south, especially birds living in Siberia, and therefore, it carries a rich source of animal diversity and serves as a link between the north and The south is home to rare species of birds. Studies show that 14 ecosystem services are affected by each other in the area of Ghareh Gheshlagh wetland and these uses are interdependent, so that without the river and canal, neither the wetland is important nor agricultural activity is possible in that area. As the studies show that the standard standardization row has been done, the distance threshold is 10813163 m and the studied data do not follow the random distribution according to Moran index of 0.62, and the p-value is zero, which indicates high correlation and clustering of the distribution. And is significant and according to z-score 150.586901454, there is less than 1% probability that this clustering pattern can be the result of a random chance that positive value values in this statistic indicate cluster data and negative value values indicate unsatisfactory data. is. However, each of the farms and ecosystem service centers of the wetland have scalable conditions and are suitable for a variety of ecosystem service traits, and on the other hand, the level and capacity of services and outgoing data in each user is easily identifiable and on the other hand sensitive to they do not prioritize ecosystem services and each has a specific application and role in the ecosystem.

Assessing the effect of sand and gravel harvesting on groundwater resources is of great importance due to being situated of underground aquifers below the surface of mines and sand production factories. The main objective of this study is to identify and evaluate the pollution of the groundwater caused by the extraction of sand and gravel in sedimented pools located in the mines of Shahriar and Qods cities. Our research indicated that so far no study has been carried out on groundwater contamination caused by the extraction as well as washing of sand and gravel. The present study was conducted in three phases: data preparation, creation of a continuous map of groundwater contamination by Simple Kriging method, and the detection of relationships and spatial correlations between qualitative parameters and gravel mines. The results indicated that levels of bicarbonate, carbonate, nitrate, sodium, potassium, chlorine, magnesium, and acidity pollution parameters of groundwater are desirable, whereas the amount of sulfate, electrical conductivity, and Total Dissolved Solids (TDS) of groundwater in the study area are higher than the standard level. The values obtained from the spatial correlation between the distance from the sand and gravel harvesting region and sulfate, electrical conductivity, as well as TDS were -0.53, -0.56, and -0.66, respectively. These values demonstrate the high correlation between these three parameters and the extraction of sand and gravel.

In spatial generalized linear mixed models, spatial correlation is assumed by adding normal latent variables to the model. In these models because of the non-Gaussian spatial response and the presence of latent variables the likelihood function cannot usually be given in a closed form, thus the maximum likelihood approach is very challenging. The main purpose of this paper is to introduce two new algorithms for the maximum likelihood estimations of parameters and to compare them in terms of speed and accuracy with existing algorithms. The presented algorithms are applied to a simulation study and their performance are compared.

Considering the spatial patterns of ecosystem services plays an important role in evaluating them. Therefore, in this study, inorder to identify and determin the spatial patterns of ecosystem services, new methods of spatial statistics such as spatial correlation of Global Moran and Anselin Moran Index and GIS were used, after quantifying recreation, aesthetic value and noise reduction ecosystem services in the study area. The results showed that the Global Moran index is up to 0.82, 0.87 and 0.89 respectively, for recreation, aesthetic value and noise reduction ecosystem services. Thus, the examined ecosystem services have a positive correlation and cluster pattern. Considering ecosystem services quantifying results with Local Moran correlation analysis related to distribution of spatial correlation of ecosystem services shown regions with maximum suitability and value of ecosystem services supply have meaningful positive spatial correlation and follow high cluster pattern, while regions with no suitability of ecosystem services supply have negative spatial correlation and low cluster pattern.

In many applications we have to encountered with bounded dependent variables. Beta regression model can be used to deal with these kinds of response variables. In this paper we aim to study spatially correlated responses in the unit interval. Initially we introduce spatial beta generalized linear mixed model in which the spatial correlation is captured through a random effect. Then the performances of the proposed model is evaluated via a simulation study, implementing Bayesian approach for parameter estimation. Finally the application of this model on two real data sets about migration rate and divorce rate in Iran are presented.

The prevailing synoptic pattern and the characteristics of the regional atmospheric circulation were studied in order to understand the predominant mechanism which governs the dry and wet spells over the southern coast of the Caspian Sea (SCCS). Monthly precipitation data from 20 weather stations located in the SCCS were analyzed for a 30-year period (1974-2003). Over this period, 10 widespread dry and 10 widespread wet months were identified for the Caspian region by investigating the spatial and temporal distributions of precipitation. Gridded precipitation data for the Middle East, provided by Asian Precipitation-Highly Resolved Observational Data Integration Towards Evaluation of the Water Resources (APHRODITE) on 0.5×0.5 degree grid along with the NCEP/NCAR reanalysis dataset on a 2.5×2.5 degree global grid were employed to determine the characteristics of the atmospheric circulation and to identify the predominant synoptic patterns during the dry and wet spells. The results indicated that the existence of a very strong ridge in the middle troposphere along with the formation of a strong anticyclone in the lower atmosphere over the northern-side of the Black Sea can be considered as the main features of the wet spells over the SCCS. The findings also indicated that the wind direction at the lower atmosphere over the Caspian Sea can be used as an appropriate criterion to separate the wet and dry spells over the SCCS so that the northerly prevailing wind during the wet spells is replaced with the southerly prevailing wind during the dry spells. Additionally, the occurrence of the dry and wet spells in the region is associated with the formation of a sea-saw pattern in vertical velocity values over the Caspian Sea. During the wet spells, formation of the descending prevailing motions over the north half of the Sea simultaneously leads to predomination of the ascending prevailing motions over the southern part. Meanwhile, during the dry spells, a reverse pattern resulting from the ascending and descending motions dominates over the Caspian region. The findings also show that it is reasonable to use the sea-level pressure changes in the Black Sea region as an appropriate index (predictor) to interpret the spatial and temporal variations of precipitation over the SCCS. In this way, during the wet spells, an increase in the sea level pressure over the Black Sea and its consequent positive feedbacks including an anticyclonic circulation over the Black Sea, northerly wind strengthening over the Caspian Sea, and air ascending over the southern part of the Caspian Sea will eventually cause an increase in precipitation over the SCCS. A reverse condition will be found in the dry spells. The investigation of the cyclones and anticyclones frequency and track during dry and wet spells indicates that the northern corridor of the Black Sea plays a very significant role in occurrence of the dry and wet spells over the SCCS. It is found that during the wet spells, the activity of the anticyclones in the northern corridor of the Black Sea is considerably increased. On the other hand, during the dry spells, a decrease in the activity of anticyclones in the north corridor is associated with a significant increase in the activity of cyclones in the region. In addition, an increase in the activity of anticyclones over the Middle East region and the Siberian high-pressure activity over the eastern-side of the Caspian Sea are taken into account as the main features of the dry spells.