Search results for "Sampling design"

Northern European Salmo trutta (L.) populations are genetically divergent across geographical regions and environmental gradients

2020

The salmonid fish Brown trout is iconic as a model for the application of conservation genetics to understand and manage local interspecific variation. However, there is still scant information about relationships between local and large-scale population structure, and to what extent geographical and environmental variables are associated with barriers to gene flow. We used information from 3,782 mapped SNPs developed for the present study and conducted outlier tests and gene–environment association (GEA) analyses in order to examine drivers of population structure. Analyses comprised >2,600 fish from 72 riverine populations spanning a central part of the species' distribution in norther…

Statistical modelling and RCS detrending methods provide similar estimates of long-term trend in radial growth of common beech in north-eastern France

2011

International audience; Dendrochronological methods have greatly contributed to the documentation of past long-term trends in forest growth. These methods primarily focus on the high-frequency signals of tree ring chronologies. They require the removal of the ageing trend in tree growth, known as 'standardisation' or 'detrending', as a prerequisite to the estimation of such trends. Because the approach is sequential, it may however absorb part of the low-frequency historical signal. In this study, we investigate the effect of a sequential and a simultaneous estimation of the ageing trend on the chronology of growth. We formerly developed a method to estimate historical changes in growth, in…

Register data in sample allocations for small-area estimation

2018

The inadequate control of sample sizes in surveys using stratified sampling and area estimation may occur when the overall sample size is small or auxiliary information is insufficiently used. Very small sample sizes are possible for some areas. The proposed allocation based on multi-objective optimization uses a small-area model and estimation method and semi-collected empirical data annually collected empirical data. The assessment of its performance at the area and at the population levels is based on design-based sample simulations. Five previously developed allocations serve as references. The model-based estimator is more accurate than the design-based Horvitz–Thompson estimator and t…

A theoretical and methodological framework for the analysis and measurement of environmental heritage at local level

2017

Abstract The study aims to assess the lived experience and the environmental heritage perceived level by residents of an high complexity rural area, and which is, in this context, the role played by production of renewable energies. The paper introduces the concept of rural capital as an effective tool for environmental heritage analysis and measurement. The proposed theoretical and methodological approach allows, in fact, its analysis in order to understand what dimensions related to territoriality are connected to the perceived level of environmental heritage at local level. Translated into operational terms, the methodology has resulted in an empirical analysis of a rural and inner area …

Perspectives on the Impact of Sampling Design and Intensity on Soil Microbial Diversity Estimates

2019

Soil bacterial communities have long been recognized as important ecosystem components, and have been the focus of many local and regional studies. However, there is a lack of data at large spatial scales, on the biodiversity of soil microorganisms; national or more extensive studies to date have typically consisted of low replication of haphazardly collected samples. This has led to large spatial gaps in soil microbial biodiversity data. Using a pre-existing dataset of bacterial community composition across a 16-km regular sampling grid in France, we show that the number of detected OTUs changes little under different sampling designs (grid, random, or representative), but increases with t…

Data quality oriented procedure, for detailed mapping of heavy metals in urban topsoil as an approach to human health risk assessment

2021

Abstract Urban soils' health is important to the community because of the soils' potential use for recreational activities. A data quality-oriented approach to sampling design is proposed for performing soil representative surveys that gives support to defensible and statistically-based decisions. Krowoderski park in Cracow (Poland) was selected as a study case to investigate heavy metals (HMs) accumulation and to assess human risk exposure according to simulated scenarios. Statistical power was computed for optimizing the number of samples to compare HMs concentration against legal upper tolerance levels (LUTL). The samples' location was iteratively designed as random spatial distribution …

Sample Design in SHARE Wave Four

2013

Sampling Design and Weighting Strategies in the Second Wave of SHARE

2008

SAMPLING DESIGN IN SHARE WAVE 7

2019

This chapter documents the sampling design adopted in SHARE. Starting with a definition of the SHARE target population, we describe the protocol that is followed to harmonise and document the sampling procedure and present the sampling frames used by the countries that recruited a baseline or refreshment sample in Wave 7. We then discuss some important aspects of the SHARE sampling design, such as stratification, clustering, variation in selection probabilities and sample composition. Finally, we provide additional information about the sampling variables included in the released SHARE dataset.

Sample design and weighting strategies in SHARE Wave 5

2015

This chapter provides a description of the sampling design and weighting strategies adopted in the fifth wave of SHARE. We begin by defining the target population that SHARE aims to represent. Next, we describe the sampling design focusing on the basic principles guiding the construction of the SHARE sample, the role played by sampling frames for coverage of the target population, and other important aspects of sampling - such as stratification, clustering and variation in selection probabilities - that affect the efficiency of sample-based inference. The chapter concludes with a description of the weighting strategies adopted by SHARE to handle problems of unit nonresponse in the baseline …