نتایج جستجو برای: spatial random effect

تعداد نتایج: 2201008  

Journal: :جنگل و فرآورده های چوب 0
زهرا نوری دانش آموخته مقطع دکتری-دانشگاه تهران محمود زبیری استاد- دانشکده منابع طبیعی-دانشگاه تهران جهانگیر فقهی دانشیار-دانشکده منابع طبیعی دانشگاه تهران محمدرضا مروی مهاجر استاد - دانشکده منابع طبیعی دانشگاه تهران

this study aims at analyzing spatial pattern and associations of fagus oriantalis lipsky in different vertical classes in intact beech forests. data collection was done in 25 ha plot in gorazbon district of educational and experimental forests of university of tehran. species and dbh of all trees with dbh > 7.5 cm were recorded. the location of each tree was determined using azimuth and distanc...

زارع, لعیا , شیخ الاسلامی , نیره , عرفانی فرد, سیدیوسف ,

Distance methods and their estimators of density may have biased measurements unless the studied stand of trees has a random spatial pattern. This study aimed at assessing the effect of spatial arrangement of wild pistachio trees on the results of density estimation by using the nearest individual sampling method in Zagros woodlands, Iran, and applying a correction factor based on the spatial p...

2002
Deng Min Li Chengming

There is inevitably error or uncertainty in spatial data, which are used to represent reality world, it will causes a suspicion for correctness of topological relations obtained by reasoning observation data. In this paper, we firstly describe the geometric and statistical properties of random line and area, and analyzing the effect of error in spatial data on representation of topological rela...

Journal: :Biometrics 2006
Brian J Reich James S Hodges Vesna Zadnik

Disease-mapping models for areal data often have fixed effects to measure the effect of spatially varying covariates and random effects with a conditionally autoregressive (CAR) prior to account for spatial clustering. In such spatial regressions, the objective may be to estimate the fixed effects while accounting for the spatial correlation. But adding the CAR random effects can cause large ch...

ژورنال: پژوهش های ریاضی 2022

The common methods for spatial risk estimation are investigated for a stationary random field. Because of simplifying, lets distribution is known, and parametric variogram for the random field are considered. In this paper, we study a nonparametric spatial method for spatial risk. In this method, we model the random field trend by a local linear estimator, and through bias-corrected residuals, ...

2010
James S. HODGES Brian J. REICH

Many statisticians have had the experience of fitting a linear model with uncorrelated errors, then adding a spatiallycorrelated error term (random effect) and finding that the estimates of the fixed-effect coefficients have changed substantially. We show that adding a spatially-correlated error term to a linear model is equivalent to adding a saturated collection of canonical regressors, the c...

 Spatial generalized linear mixed models are used commonly for modelling non-Gaussian discrete spatial responses. We present an algorithm for parameter estimation of the models using Laplace approximation of likelihood function. In these models, the spatial correlation structure of data is carried out by random effects or latent variables. In most spatial analysis, it is assumed that rando...

Journal: :جنگل و فرآورده های چوب 0
فریده امیدوار حسینی دانشجوی کارشناسی ارشد رشتۀ جنگلداری، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات تهران، تهران، ایران رضا اخوان استادیار پژوهش، مؤسسۀ تحقیقات جنگل ها و مراتع کشور، تهران، ایران هادی کیادلیری استادیار گروه جنگلداری، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات، تهران، ایران اسداله متاجی دانشیار گروه جنگلداری، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات، تهران، ایران

one of the most visible aspects of a forest stand structure is the spatial patterns of trees. competition affects on forest structure and its understanding is important, when the purpose of forest management is to imitate the dynamic of natural ecosystems. for this purpose, an unmanaged intact forest was selected with 26 hectares area. all chestnut leaf oak (quercus castaneifolia) trees with a ...

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