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| Registros recuperados: 13 | |
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| Martínez Martínez, Talina Olivia. |
| La calidad sanitaria en los productos hortofrutícolas debe considerarse una prioridad en la producción de alimentos. Actualmente en México, existe una gran preocupación por las asociaciones de productores y gobierno federal para adoptar sistemas de producción que reduzcan riesgos de contaminación (SRRC). Para la implementación de estos sistemas, es necesario cumplir con una serie de requisitos, entre ellos se encuentra la validación de procesos. Un método inmediato para efectuar este requerimiento, es la evaluación de la calidad sanitaria desde el punto de vista microbiológico y toxicológico, lo que hace necesario determinar un plan de muestreo y las técnicas apropiadas para la detección y cuantificación de patógenos indicadores. Con este propósito, en... |
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Palavras-chave: Salmonella; Escherichia coli; Pesticides; Phenolic compounds; Survival; Sample size; Entomología y Acarología; Doctorado. |
| Ano: 2011 |
URL: http://hdl.handle.net/10521/590 |
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| Beliaeff, Benoit; Burgeot, Thierry. |
| Activity of 7-ethoxyresorufin-O-deethylase (EROD) in fish is certainly the best-studied biomarker of exposure applied in the field to evaluate biological effects of contamination in the marine environment. Since 1991, a feasibility study for a monitoring network using this biomarker of exposure has been conducted along French coasts. Using data obtained during several cruises, this study aims to determine the number of fish required to detect a given difference between 2 mean EROD activities, i.e. to achieve an a priori fixed statistical power (l-beta) given significance level (alpha), variance estimations and projected ratio of unequal sample sizes (k). Mean EROD activity and standard error were estimated at each of 82 sampling stations. The... |
| Tipo: Text |
Palavras-chave: Biomonitoring; Estimation; EROD activity; Statistical power; Sample size; Sampling design. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00337/44787/44483.pdf |
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| Rossetti,Adroaldo Guimarães; Vidal Neto,Francisco das Chagas; Barros,Levi de Moura. |
| Abstract: The objective of this work was to estimate sample sizes of cashew (Anacardium occidentale) nuts as an aid to the genetic improvement of cashew tree. Nuts were separated by size: nuts < 17 mm were classified as size 1 (S1); 17 mm ≤ nuts < 19 mm, size 2 (S2); 19 mm ≤ nuts < 23 mm, size 3 (S3); 23 mm ≤ nuts < 25 mm, size 4 (S4); and nuts ≥ 25 mm, size 5 (S5). Sizing the sample for each stratum depends on the variance of nut size and on the error level B allowed for either the estimates or the desired precision in the results. The sample size will be larger the greater the variance of the stratum, the lower the error level allowed for the estimates, or the greater the precision desired in the results. For an error B = 0.2 g, the sample... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Anacardium occidentale; Sample size; Sampling precision; Uniform stratified random sampling. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2019000102000 |
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| Harrison, David A.; Brady, Anthony R.. |
| The standard formulas for sample size and power calculation, as implemented in the command sampsi, make use of a normal approximation to the t-distribution. When the sample sizes are small, this approximation is poor, resulting in overestimating power (or underestimating sample size). One particular situation in which this is likely to be important is the field of cluster randomized trials. Although the total number of individuals in a cluster randomized trial may be large, the number of clusters will often be small. We present a simulation study from the design of a cluster randomized crossover trial that motivated this work and a command to perform more accurate sample size and power calculations based on the noncentral t-distribution. |
| Tipo: Journal Article |
Palavras-chave: Sampncti; Sample size; Power; Noncentral t-distribution; Research Methods/ Statistical Methods. |
| Ano: 2004 |
URL: http://purl.umn.edu/116234 |
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| Storck,Lindolfo; Kobata,Sarha G. K.; Brum,Betania; Soares,André B.; Modolo,Alcir J.; Assmann,Tangriani S.. |
| ABSTRACT This study aimed to estimate the size of blocks of observations of resistance to penetration, obtained by a motorized digital penetrometer, and the number of blocks with semi-amplitude of the confidence interval between 5 and 20% of the mean penetration resistance, for different soil depth ranges and cone diameters. Data were collected in two contrasting plots of a crop-livestock integration experiment, located in Abelardo Luz, SC, Brazil. Ten blocks were delimited and the resistance to penetration was determined in 20 points spaced by 20 cm, using a motorized digital soil penetrometer. To estimate the mean of resistance to penetration, 12 blocks of four points per experimental plot should be used for a semi-amplitude of the confidence interval... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Sample size; Penetration resistance; Grazing pressure; Soil management. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662016000300250 |
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| Storck,Lindolfo; Antúnez,Claudia Carolina Cabral; Guedes,Jerson Vanderlei Carús; Cargnelutti Filho,Alberto; Alvarez,Jimmy Walter Rasche. |
| ABSTRACT Estimates of diversity indices provide information on distribution, richness and abundance of species within a community. The aim of the current study was to estimate faunistic indices (richness, constancy, dominance and abundance) of the species collected by beat cloth and entomological net sampling methods in different soybean crops and to determine the sample size necessary to estimate faunistic indices. Fauna density from 100 soybeans crops located in nine municipalities in Rio Grande do Sul, Brazil, were evaluated. Thirty points, 20 meters apart from one another, were marked in the crops. At each point, insect pests and natural enemies were collected using the two sampling methods. Faunistic indices, including the average and interval... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Glycine max; Resampling; Sample size; Natural enemies; Sampling methods. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162016000600559 |
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| Facco,Giovani; Cargnelutti Filho,Alberto; Alves,Bruna Mendonça; Burin,Cláudia; Santos,Gustavo Oliveira dos; Kleinpaul,Jéssica Andiara; Neu,Ismael Mario Márcio. |
| ABSTRACT: The objectives of this study were to determine the sample size, in terms of number of plants, needed to estimate the average values of productive traits of the pigeon pea and to determine whether the sample size needed varies between traits and between crop years. Separate uniformity trials were conducted in 2011/2012 and 2012/2013. In each trial, 360 plants were demarcated, and the fresh and dry masses of roots, stems, and leaves and of shoots and the total plant were evaluated during blossoming for 10 productive traits. Descriptive statistics were calculated, normality and randomness were checked, and the sample size was calculated. There was variability in the sample size between the productive traits and crop years of the pigeon pea culture.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Cajanus cajan L.; Sample size; Experimental precision.. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782016000400619 |
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| Cargnelutti Filho,Alberto; Beltrame,Rafael; Bisognin,Dilson Antônio; Lazarotto,Marília; Haselein,Clovis Roberto; Gatto,Darci Alberto; Santos,Gleison Augusto dos. |
| ABSTRACT: In eucalyptus crops, it is important to determine the number of plants that need to be evaluated for a reliable inference of growth. The aim of this study was to determine the sample size needed to estimate average trunk diameter at breast height and plant height of inter-specific eucalyptus hybrids. In 6,694 plants of twelve inter-specific hybrids it was evaluated trunk diameter at breast height at three (DBH3) and seven years (DBH7) and tree height at seven years (H7) of age. The statistics: minimum, maximum, mean, variance, standard deviation, standard error, and coefficient of variation were calculated. The hypothesis of variance homogeneity was tested. The sample size was determined by re sampling with replacement of 10,000 re samples. There... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Eucalyptus spp.; Number of plants; Sample size; Experimental planning.. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782016000701192 |
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| Registros recuperados: 13 | |
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