How should a spatial-coverage sample design for a geostatistical soil survey be supplemented to support estimation of spatial covariance parameters?
How should a spatial-coverage sample design for a geostatistical soil survey be supplemented to support estimation of spatial covariance parameters?
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DOI：
10.1016/j.geoderma.2017.12.022
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发表时间：
2018-06
期刊：
影响因子：
6.1
通讯作者：
R. Lark;B. Marchant
中科院分区：
文献类型：
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作者：
R. Lark;B. Marchant
我们使用一个表达式的误差方差的地质统计预测，其中包括在空间协方差参数的不确定性的影响，以检查样本设计的性能，其中的一部分，总数量的观测分布根据空间覆盖设计，其余的观测添加在补充关闭位置。该表达式已被用于以前的研究空间抽样的数值优化，本研究的目的是使用它来发现简单的经验法则，为实际的地质统计抽样。一系列的样本量和对比属性的基础随机变量的结果表明，有一个改进，只是增加了几个样本点和密切的对，和一个相当缓慢的增加，在预测误差方差的比例，以这种方式分配的样本点增加到总样本量的10%至20%以上。因此，人们可以提出一个经验法则，对于固定的样本量，90%的样本站点根据空间覆盖设计分布，然后在距离较大子集中的站点较短的距离处添加10%，以支持空间协方差参数的估计。
We use an expression for the error variance of geostatistical predictions, which includes the effect of uncertainty in the spatial covariance parameters, to examine the performance of sample designs in which a proportion of the total number of observations are distributed according to a spatial coverage design, and the remaining observations are added at supplementary close locations. This expression has been used in previous studies on numerical optimization of spatial sampling, the objective of this study was to use it to discover simple rules of thumb for practical geostatistical sampling. Results for a range of sample sizes and contrasting properties of the underlying random variables show that there is an improvement on adding just a few sample points and close pairs, and a rather slower increase in the prediction error variance as the proportion of sample points allocated in this way is increased above 10 to 20% of the total sample size. One may therefore propose a rule of thumb that, for a fixed sample size, 90% of sample sites are distributed according to a spatial coverage design, and 10% are then added at short distances from sites in the larger subset to support estimation of spatial covariance parameters.