A sample coordination method to monitor totals of environmental variables

Abstract

A new sampling strategy for design‐based environmental monitoring is proposed. It has the potential to produce superior estimators for totals of environmental variables and their changes over time. In the strategy, we combine two concepts known as spatially balanced sampling and coordination of samples. Spatially balanced sampling can provide superior estimators of totals, while coordination of samples over time is often used to improve estimators of change. Compared with reference strategies, we show that the new strategy can improve the precision of the estimators of totals and their change simultaneously. A forest inventory application is used to illustrate the new strategy and the results can be summarized as (i) using auxiliary information to spread the sample can improve the estimators of totals; (ii) a positive coordination of the samples reduced the variance of the estimator of change by more than 37% compared with independent samples; and (iii) a high overlap between successive samples does not guarantee a good estimator of change. The presented strategy can be used to develop more efficient environmental monitoring programs.

Basic Multivariate Statistical Methods for Environmental Monitoring Data Mining: Introductory Course for Master Students

“…In the references some major textbook are given and each one of them could be source of additional information on the theory and application of chemometrics and environmetrics for data interpretation and modelling. Additional small selection of applications of exploratory data analysis are offered for individual work and seminars [12][13][14][15][16][17].…”

Estimation of change with partially overlapping and spatially balanced samples

“…Similar to the variance estimator (7), the covariance estimator ( 12) is proposed as a general estimator for spatially balanced samples. In the next section, we study the performance of the proposed variance and covariance estimators, specifically under the strategy in Zhao and Grafström (2020).…”

“…Regarding the monitoring of change, we need to be cautious about the determination of whether a sampling strategy is an efficient strategy or not. Zhao and Grafström (2020) proposed an efficient sampling strategy for monitoring the change of environmental variables. In this strategy, the concept of spatially balanced samples and positive sample coordination are combined.…”

“…These designs offer advantages over traditional random sampling methods by capturing a representative range of environmental conditions and reducing the potential bias introduced by clustering or spatial autocorrelation. Furthermore, recent studies by Zhao and Grafström (2020) have demonstrated the benefits of employing spatially balanced and partially overlapping samples for monitoring changes in environmental variables, leading to improved efficiency and reduced variance in state and change estimators.…”

Sampling-Based Approaches to Estimating Two-Dimensional Large Wood Area from UAS Imagery

“…There were a total of 3858 non-forested hexagons that comprised our sampling frame (Figure 1). In retrospect we would have simply drawn from this non-forested population to simplify plot expansion However, for the sake of simplifying the analysis, we use a finite population approach [17] where each hexagon was considered as a population unit in order to estimate LW total area.…”