A Test of Random Versus Systematic Ecological Samplig

Bourdeau, Philippe F.

doi:10.2307/1929722

Cited by 34 publications

(29 citation statements)

References 12 publications

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“…These results were effectively reversed in unclustered populations, where all 13 estimators underestimated the true variance (a, h, m), with v 8 and v W being the most, rather than the least, biased (a, g, h, m The problem of estimating the variance of the systematic sample mean was fi rst addressed in Scandinavian forestry in the 1920s and 1930s (Heikkinen 2006 ), and later in North American forestry (Hasel 1938, Osborne 1942, Finney 1948, Bourdeau 1953. A series of studies by statistical sampling theorists from the 1940s onward, fi rst reviewed by Buckland ( 1951 ), extended Cochran ' s idea of a superpopulation model to investigate statistical properties of estimators in spatial populations where systematic sampling was more precise (Quenouille 1949, Das 1950, Jowett 1952, Williams 1956, Hannan 1962, Iachan 1982, Bellhouse and Sutradhar 1988.…”

Section: Testing Variance Estimators For Systematic Surveysmentioning

confidence: 99%

“…Some of this work (Madow andMadow 1944 , Cochran 1946 ) was done assuming linear populations were to be sampled, such as an alphabetic list of households to be surveyed by telephone. A parallel succession of studies undertaken in the population biological literature (Bourdeau 1953 ), notably for application to sampling a two-dimensional space, surveying forests for timber yield estimation (Hasel 1938, Finney 1948, concluded that the precision advantage of systematic designs was minor and that random sampling is preferred (Greig-Smith 1983 ). More recent statistical investigation (D ' Orazio 2003, Wolter 2007 ) assumed systematic sampling to be more precise in autocorrelated populations and focused on the still unsolved problem of how to reliably estimate the variance of the estimate of the mean from a systematic survey for linear (Wolter 1984(Wolter , 2007 and two-dimensional (i.e., spatial) populations (D ' Orazio 2003 ).…”

Section: Introductionmentioning

confidence: 99%

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Precision of systematic and random sampling in clustered populations: habitat patches and aggregating organisms

McGarvey¹,

Burch²,

Matthews³

2015

Ecological Applications

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Section: Testing Variance Estimators For Systematic Surveysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Precision of systematic and random sampling in clustered populations: habitat patches and aggregating organisms

McGarvey¹,

Burch²,

Matthews³

2015

Ecological Applications

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“…The use of different sampling strategies and their effects on the results and their ecological interpretation has been under intensive debate since the early 1950s [1]. It is a well-established fact that sampling strategy is one of the most important factors influencing the observed patterns and processes in ecological studies [2,3].…”

Section: Introductionmentioning

confidence: 99%

A performance comparison of sampling methods in the assessment of species composition patterns and environment–vegetation relationships in species-rich grasslands

et al. 2017

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The influence that different sampling methods have on the results and the interpretation of vegetation analysis has been much debated, but little is yet known about how the spatial arrangement of samples affect patterns of species composition and environment-vegetation relationships within the same vegetation type. We compared three data sets of the same sample size obtained by three standard sampling methods: preferential, random, and systematic. These different sampling methods were applied to a study area comprising of 36 ha of intermittently wet Molinia meadows. We compared the performance of the three methods under two management categories: managed (extensively mown) and unmanaged (abandoned for 10 years). A total of 285 vegetation-plots were sampled, with 95 plots recorded per sampling method. In preferential sampling, we sampled only patches of vegetation with an abundance of indicator species of the habitat type, while random and systematic plots were positioned independently from the researcher by using GIS. The effect of each sampling method on the patterns of species composition and species-environment relationships was explored by redundancy analysis and the significance of effects was tested by the randomization test. Preferential sampling revealed different patterns of species composition than random and systematic sampling methods. Random and systematic sampling methods have resulted in broader vegetation variability than with preferential sampling method. Preferential sampling revealed different relationship between soil parameters and species composition in contrast to random and systematic sampling methods. Although we have not found significant differences in vegetation-environment relationships between random and systematic sampling methods, random sampling revealed a more robust correlation of species data to soil factors than preferential and systematic sampling methods. Intentional restriction of vegetation variation sampled preferentially may be detrimental to statistical inference in studies of species composition patterns and vegetation-environment relationships.

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“…Sampling precision proved that all areas were reliably sampled (Table 1), according to the described by Bordeau (1953) and Goldsmith & Harrison (1976), who established that the variance of sample means increases in the reverse order to the number of sites sampled per area. Barbour et al (1998) have consolidated sampling precision in defining that the inverse of the variance (eq.…”

Section: Resultsmentioning

confidence: 92%

Weed Occurrence in Sugarcane as Function of Variety and Ground Straw Management1

et al. 2016

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-This study aims to verify the effect of crop varietal architecture and straw removal from planting rows in the occurrence of weeds in sugarcane and infer about the sustainability of the production system with no herbicide application. The experiment was established in 2011 in a randomized block design with split plots and four replications. Main plots were varieties IACSP95 5000 and SP91 1049. In the sub-plots there the straw removal was allocated (evenly scattered in the area, or concentrated in inter-rows). Assessments were conducted in 2012 and 2013 and the absolute levels of infestation, density, frequency and dominance of weed species were obtained. Areas were intra-characterized by the coefficients of Simpson and Shannon-Weiner and sustainability inferred by the SEP coefficient. Areas were grouped by the similarity coefficient of Jaccard. Other factors besides leaf architecture were more significant for level of infestation. Treatments with straw removal from planting rows were more infested than those with evenly scattered straw. In the second year of cultivation, those species most adapted to the system increased their importance value. Wild poinsettia was the dominant weed in all treatments, deserving attention from pre-planting on, to reducing its occurrence in the soil seed bank. Species diversity was higher where straw was evenly scattered due to the occurrence of species other than wild poinsettia. Sustainability was reduced from the first to the second year, indicating that only cultural practices are not enough, even with high shading provided by crop and straw production, demanding herbicides.Keywords: Saccharum spp., phytosociology, sustainability. RESUMO -Objetivou-se com o presente trabalho verificar o efeito da arquitetura varietal da cultura e da aplicação da prática de desaleiramento na ocorrência de plantas daninhas em áreas de cultivo de cana-de-açúcar, bem como inferir sobre a sustentabilidade do sistema produtivo sem aplicação de herbicidas. O experimento foi implantado em 2011 em delineamento experimental de blocos casualizados com parcelas subdivididas, com quatro repetições. As parcelas foram compostas pelas variedades IACSP95 5000 e SP91 1049. Nas subparcelas, alocou-se o manejo do palhiço (desaleirado ou não desaleirado). As avaliações foram realizadas nos anos de 2012 e 2013, sendo obtidos os níveis absolutos de infestação, a densidade, a frequência e a dominância das espécies de plantas daninhas. As áreas foram intra-caracterizadas pelos coeficientes de Simpson e Shannon

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A Test of Random Versus Systematic Ecological Samplig

Cited by 34 publications

References 12 publications

Precision of systematic and random sampling in clustered populations: habitat patches and aggregating organisms

Precision of systematic and random sampling in clustered populations: habitat patches and aggregating organisms

A performance comparison of sampling methods in the assessment of species composition patterns and environment–vegetation relationships in species-rich grasslands

Weed Occurrence in Sugarcane as Function of Variety and Ground Straw Management1

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