Sampling design

Quantifying landscape characteristics and linking them to ecological processes is one of the central goals of landscape ecology. Landscape metrics are a widely used tool for the analysis of patch-based, discrete land-cover classes. Existing software to calculate landscape metrics has several constraints, such as being limited to a single platform, not being open-source or involving a complicated integration into large workflows. We present landscapemetrics, an open-source R package that overcomes many constraints of existing landscape metric software. The package includes an extensive collection of commonly used landscape metrics in a tidy workflow. To facilitate the integration into large workflows, landscapemetrics is based on a well-established spatial framework in R. This allows pre-processing of land-cover maps or further statistical analysis without importing and exporting the data from and to different software environments. Additionally, the package provides many utility functions to visualize, extract, and sample landscape metrics. Lastly, we provide building-blocks to motivate the development and integration of new metrics in the future. We demonstrate the usage and advantages of landscapemetrics by analysing the influence of different sampling schemes on the estimation of landscape metrics. In so doing, we demonstrate the many advantages of the package, especially its easy integration into large workflows. These new developments should help with the integration of landscape analysis in ecological research, given that ecologists are increasingly using R for the statistical analysis, modelling and visualization of spatial data.

This study was conducted in order to examine the factors that influence customers’ intention to purchase Malaysian made cars. The objectives of this study are: (i) To investigate the relationship between service quality, product quality and price fairness with customer satisfaction and trust; (ii) To investigate the relationship between the customer satisfaction with trust and purchase intention; (iii) To identify the relationship between the service quality, product quality and price fairness with customer satisfaction. Structural Equation Modeling (SEM) was employed and analysed using AMOS software. Stratified sampling design used in selecting 120 employees as the respondent for the study. The result revealed that only product quality and price fairness leads to customer satisfaction. Meanwhile, customer satisfaction will lead to trust, and trust influences the purchase intention.

Accurate quantification of stormwater pollutant levels is essential for estimating overall contaminant discharge to receiving waters. Numerous sampling approaches exist that attempt to balance accuracy against the costs associated with the sampling method. This study employs a novel and practical approach of evaluating the accuracy of different stormwater monitoring methodologies using stormflows and constituent concentrations produced by a fully validated continuous simulation watershed model. A major advantage of using a watershed model to simulate pollutant concentrations is that a large number of storms representing a broad range of conditions can be applied in testing the various sampling approaches. Seventy-eight distinct methodologies were evaluated by “virtual samplings” of 166 simulated storms of varying size, intensity and duration, representing 14 years of storms in Ballona Creek near Los Angeles, California. The 78 methods can be grouped into four general strategies: volume-paced compositing, time-paced compositing, pollutograph sampling, and microsampling. The performances of each sampling strategy was evaluated by comparing the (1) median relative error between the virtually sampled and the true modeled event mean concentration (EMC) of each storm (accuracy), (2) median absolute deviation about the median or “MAD” of the relative error or (precision), and (3) the percentage of storms where sampling methods were within 10% of the true EMC (combined measures of accuracy and precision). Finally, costs associated with site setup, sampling, and laboratory analysis were estimated for each method. Pollutograph sampling consistently outperformed the other three methods both in terms of accuracy and precision, but was the most costly method evaluated. Time-paced sampling consistently underestimated while volume-paced sampling over estimated the storm EMCs. Microsampling performance approached that of pollutograph sampling at a substantial cost savings. The most efficient method for routine stormwater monitoring in terms of a balance between performance and cost was volume-paced microsampling, with variable sample pacing to ensure that the entirety of the storm was captured. Pollutograph sampling is recommended if the data are to be used for detailed analysis of runoff dynamics.

Summary 1. No-take reserves are a common tool for fisheries management and biodiversity conservation in marine ecosystems. Despite much discussion of their benefits, data documenting many reserve effects are surprisingly scarce. Several studies have also been criticized for a lack of rigour so that changes within reserves cannot be separated from underlying natural variation and attributed unequivocally to protection.

The combined use of data obtained from different analytical instruments is a complex problem.In this paper the potential of coupling three analytical techniques for building a class model for extra virgin (e.v.) olive oil from Liguria, was investigated.A sampling design for the Ligurian e.v. olive oil was developed by the selection of a representative subset from all possible e.v. olive oil samples of the Liguria region.Thus, in order to choose this subset with uniform distribution on the production area and representative of the production density, two algorithms for sampling have been used: Kennard–Stone and Potential Function.The samples were analysed by head-space mass spectrometry (electronic nose), UV–visible and NIR spectroscopy.In particular, the exceptional possibility provided by Chemometrics to effectively extract and combine (fusion) the information from these multivariate and non-specific data and to build a class model for Liguria e.v. olive oil was studied.

Yellow sticky-traps and a modified Johnson-Taylor suction-trap were used to index the relative population dynamic of leafhoppers associated with sesame in the east Mediterranean region of Turkey. Comparison of the obtained results signified important differences between both traps. 32 leafhoppers species were caught in the suction-trap while only 18 species were determined on yellow sticky-traps. For most of the leafhopper species, relatively more males were determined on the yellow-traps than in the suction-trap, indicating a higher activity of male leafhoppers during daytime hours. A close relationship between the seasonal flight pattern as indexed by sticky-traps and by suction-trap was only observed forAsymmetrasca decedens (Paoli) andEmpoasca decipiens Paoli. For most other leafhopper species no or only a very poor correlation for the relative population dynamic was determined between both traps. Important leafhopper vector species, e.g.,Circulifer haematoceps (Mulsant et Rey) andOrosius orientalis (Matsumura) were better represented in yellow sticky-trap catches than they were in the suction trap. Die relative Populationsdynamik der mit Sesam assozüerten Zwergzikaden wurde mit beleimten Gelbtafeln und einer stationären Johnson-Taylor-Saugfalle an der südöstlichen Mittelmeerküste der Türkei untersucht. Beim Vergleich beider Methoden zeigten sich deutliche Unterschiede zwischen den Fallentypen. In der Saugfalle konnten 32 Zwergzikadenarten erfaßt werden, während dies auf den Gelbtafeln nur 18 Arten waren. Die meisten Zwergzikadenarten zeigten auf den Gelbtafeln ein stark in Richtung der Männchen verschobenes Geschlechterverhältnis, was eine erhöhte Flugaktivität der Männchen während des Tageslichts vermuten läßt. Auch der Verlauf der saisonalen Flugaktivität war für die meisten Zwergzikadenarten zwischen den beiden Fallentypen sehr unterschiedlich, und es konnten zwischen Saug- und Gelbfalle keine deutlichen Korrelationen hergestellt werden. Nur für die beiden zusammen erfaßten ArtenAsymmetrasca decedens (Paoli) undEmpoasca decipiens Paoli wurde ein enger Zusammenhang zwischen der mit der Saugfalle und den gelben Leimtafeln erfaßten relativen Populationsdynamik festgestellt. Wichtige Vektorenarten unter den Zwergzikaden, z. B.Circulifer haematoceps (Mulsant et Rey) undOrosius orientalis (Matsumura) waren auf den Gelbtafeln besser repräsentiert als in der Saugfalle.

The determinination of an adequate collection protocol for protists is critical in the examination of their distribution and composition in temperate headwater streams. The objective of this study was to test which sampling design/sample gear combination would yield a cost-effective, site-representative protist assemblage. Defining parameters included greatest taxa richness, abundance, morphological diversity, taxa overlap, and cell-size diversity. Two sample designs (i.e., transect and mesohabitat design) and two sample gears (i.e., benthic grab sample, and a colonizing device [polyurethane foam unit, PFU]) were tested in three 100-m reaches representing the predominant environmental conditions (i.e., fragmented woodlots and agriculture) in the study area. A two-way ANOVA was used to evaluate abundance taxa richness and abundance of the protist assemblage (fixed effects) across the three reaches (random effects). The mesohabitat sampling design had the highest mean in both taxa richness (n = 72, P = 0.0012) and abundance (n = 72, P = 0.0004). The highest mean was reported with the benthic grab sampler (39.89 ± 1.1) in the abundance count only (n = 72, P < 0.0001). There was no difference in the design and gear interaction. Morphological diversity, cell-size diversity and percent taxa overlap between sampling design/sample gear combinations also were examined. A higher taxa overlap of the top 10% most abundant taxa was observed with the benthic grab sampler (43–100%) versus the PFU (25–69%); however, the greatest morphological and cell-size diversity was produced by the transect design/PFU combination. We conclude a “hybrid” of the two sample designs will account for “patchy” distributional patterns of protists and use of the PFU, because of the highest yield in morphological and cell-size diversity, will provide the most cost-effective, site-representative protist assemblage in temperate headwater streams.

Abstract. Low-discrepancy point distributions exhibit excellent uniformity properties for sampling in applications such as rendering and measurement. We present an algorithm for generating low-discrepancy point distributions on arbitrary parametric surfaces using the idea of converting the 2D sampling problem into a 1D problem by adaptively mapping a space-filling curve onto the surface. The 1D distribution takes into account the parametric mapping by employing a corrective approach similar to histogram equalisation to ensure ...

Objective: The main interest of this article is to explain one of the most common incidences that occur during the drawing of random samples: over-representation of social categories. Method: In that sense, the population sample obtained as a result of the accomplishment of the ERP’s study has been compared with EPA’s population sample. An important women’s over-representation has been localized in ERP’s population sample, as well other socio-demographic differences. In that sense, an explanatory hypothesis of the differences was suggested. Results: Taking into account the developed analysis we could conclude that the root of women’s over-representation in ERP’s population sample was 1) caused, from a methodological point of view, by definition of units of analysis and units of sampling and by interviewing techniques used to interview and capture these units; 2) and made possible, from a societal point of view, by gendered division of labour.

... L. AMBROSIO.J, DORADO^ AND JP, DEL MONTE* Dpto de Ecoiiomia v Ciencias Sociales Agrurias. ... It was found that, in order to estimate the number of weed seeds in soil with a desirable de-gree of accuracy and confidence level, fhe sam-ple size depends to large extent on ...