Efficiency evaluation of MEV spatial sampling strategies: a scenario analysis

2006 ◽  
Vol 50 (3) ◽  
pp. 878-890 ◽  
Author(s):  
Giovanni Lafratta
Keyword(s):  
Scenario Analysis ◽  
Spatial Sampling ◽  
Efficiency Evaluation ◽  
Sampling Strategies

scholarly journals Accounting for spatial sampling patterns in Bayesian phylogeography

2021 ◽  
Vol 118 (52) ◽  
pp. e2105273118
Author(s):  
Stéphane Guindon ◽  
Nicola De Maio
Keyword(s):  
Bayesian Modeling ◽  
Evolutionary Process ◽  
Simulated Data ◽  
Spatial Sampling ◽  
Statistical Computing ◽  
Sampling Strategies ◽  
Demographic Dynamics ◽  
Genetic Sequences ◽  
Statistical Phylogeography ◽  
Modeling Data

Statistical phylogeography provides useful tools to characterize and quantify the spread of organisms during the course of evolution. Analyzing georeferenced genetic data often relies on the assumption that samples are preferentially collected in densely populated areas of the habitat. Deviation from this assumption negatively impacts the inference of the spatial and demographic dynamics. This issue is pervasive in phylogeography. It affects analyses that approximate the habitat as a set of discrete demes as well as those that treat it as a continuum. The present study introduces a Bayesian modeling approach that explicitly accommodates for spatial sampling strategies. An original inference technique, based on recent advances in statistical computing, is then described that is most suited to modeling data where sequences are preferentially collected at certain locations, independently of the outcome of the evolutionary process. The analysis of georeferenced genetic sequences from the West Nile virus in North America along with simulated data shows how assumptions about spatial sampling may impact our understanding of the forces shaping biodiversity across time and space.

scholarly journals Impact of satellite viewing-swath width on global and regional aerosol optical thickness statistics and trends

2014 ◽  
Vol 7 (7) ◽  
pp. 2313-2335 ◽  
Author(s):  
P. R. Colarco ◽  
R. A. Kahn ◽  
L. A. Remer ◽  
R. C. Levy
Keyword(s):  
Optical Thickness ◽  
Radiative Forcing ◽  
Aerosol Optical Thickness ◽  
Spatial Sampling ◽  
Sampling Strategies ◽  
Data Set ◽  
Modis Data ◽  
Aerosol Loading ◽  
The Impact ◽  
Single Pixel

Abstract. We use the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite aerosol optical thickness (AOT) product to assess the impact of reduced swath width on global and regional AOT statistics and trends. Along-track and across-track sampling strategies are employed, in which the full MODIS data set is sub-sampled with various narrow-swath (~ 400–800 km) and single pixel width (~ 10 km) configurations. Although view-angle artifacts in the MODIS AOT retrieval confound direct comparisons between averages derived from different sub-samples, careful analysis shows that with many portions of the Earth essentially unobserved, spatial sampling introduces uncertainty in the derived seasonal–regional mean AOT. These AOT spatial sampling artifacts comprise up to 60% of the full-swath AOT value under moderate aerosol loading, and can be as large as 0.1 in some regions under high aerosol loading. Compared to full-swath observations, narrower swath and single pixel width sampling exhibits a reduced ability to detect AOT trends with statistical significance. On the other hand, estimates of the global, annual mean AOT do not vary significantly from the full-swath values as spatial sampling is reduced. Aggregation of the MODIS data at coarse grid scales (10°) shows consistency in the aerosol trends across sampling strategies, with increased statistical confidence, but quantitative errors in the derived trends are found even for the full-swath data when compared to high spatial resolution (0.5°) aggregations. Using results of a model-derived aerosol reanalysis, we find consistency in our conclusions about a seasonal–regional spatial sampling artifact in AOT. Furthermore, the model shows that reduced spatial sampling can amount to uncertainty in computed shortwave top-of-atmosphere aerosol radiative forcing of 2–3 W m−2. These artifacts are lower bounds, as possibly other unconsidered sampling strategies would perform less well. These results suggest that future aerosol satellite missions having significantly less than full-swath viewing are unlikely to sample the true AOT distribution well enough to obtain the statistics needed to reduce uncertainty in aerosol direct forcing of climate.

Comparison of spatial sampling strategies for ground sampling and validation of MODIS LAI products

2014 ◽  
Vol 35 (20) ◽  
pp. 7230-7244 ◽  
Author(s):  
Yanling Ding ◽  
Yong Ge ◽  
Maogui Hu ◽  
Jinfeng Wang ◽  
Jianghao Wang ◽  
...  
Keyword(s):  
Spatial Sampling ◽  
Sampling Strategies ◽  
Modis Lai

scholarly journals Spatial Sampling Strategies for the Effect of Interpolation Accuracy

2015 ◽  
Vol 4 (4) ◽  
pp. 2742-2768 ◽  
Author(s):  
Hairong Zhang ◽  
Lijiang Lu ◽  
Yanhua Liu ◽  
Wei Liu
Keyword(s):  
Spatial Sampling ◽  
Sampling Strategies ◽  
Interpolation Accuracy

scholarly journals Monitoring riverine fish communities through eDNA metabarcoding: determining optimal sampling strategies along an altitudinal and biodiversity gradient

2018 ◽  
Vol 2 ◽  
Author(s):  
Jonas Bylemans ◽  
Dianne M. Gleeson ◽  
Mark Lintermans ◽  
Christopher M. Hardy ◽  
Matthew Beitzel ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Species Abundance ◽  
Spatial Sampling ◽  
Optimal Sampling ◽  
Sampling Strategies ◽  
Sampling Intensity ◽  
Fish Biodiversity ◽  
Adequate Sampling ◽  
Riverine Fish ◽  
The Impact

Monitoring aquatic biodiversity through DNA extracted from environmental samples (eDNA) combined with high-throughput sequencing, commonly referred to as eDNA metabarcoding, is increasing in popularity within the scientific community. However, sampling strategies, laboratory protocols and analytical pipelines can influence the results of eDNA metabarcoding surveys. While the impact of laboratory protocols and analytical pipelines have been extensively studied, the importance of sampling strategies on eDNA metabarcoding surveys has not received the same attention. To avoid underestimating local biodiversity, adequate sampling strategies (i.e. sampling intensity and spatial sampling replication) need to be implemented. This study evaluated the impact of sampling strategies along an altitudinal and biodiversity gradient in the upper section of the Murrumbidgee River (Murray-Darling Basin, Australia). An eDNA metabarcoding survey was used to determine the local fish biodiversity and evaluate the influence of sampling intensity and spatial sampling replication on the biodiversity estimates. The results show that optimal eDNA sampling strategies varied between sites and indicate that river morphology, species richness and species abundance affect the optimal sampling intensity and spatial sampling replication needed to accurately assess the fish biodiversity. While the generality of the patterns will need to be confirmed through future studies, these findings provide a basis to guide future eDNA metabarcoding surveys in river systems.

Who owns a personal home page?

2003 ◽  
Vol 62 (2) ◽  
pp. 121-129 ◽  
Author(s):  
Astrid Schütz ◽  
Franz Machilek
Keyword(s):  
Search Engine ◽  
Home Page ◽  
Sampling Strategies ◽  
Home Pages ◽  
Personal Home Pages ◽  
Age And Sex

Research on personal home pages is still rare. Many studies to date are exploratory, and the problem of drawing a sample that reflects the variety of existing home pages has not yet been solved. The present paper discusses sampling strategies and suggests a strategy based on the results retrieved by a search engine. This approach is used to draw a sample of 229 personal home pages that portray private identities. Findings on age and sex of the owners and elements characterizing the sites are reported.

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