Samples subsampling

Three- Stage Sampling (Strata, Samples, Subsamples)... 

There are various types of samples within given sampling schemes, e.g., bulk samples > primary samples > gross samples > subsamples > test samples > measuring samples —Fig. 2.4... 

Other designations for samples are bulk sample, primary sample, secondary sample, subsample, laboratory sample, and test sample. These terms are used when a sample of a bulk system is divided, possibly a number of times, before actually used in an analysis. For example, a water sample from a well... 

Differentiate between bulk sample, primary sample, secondary sample, subsample, laboratory sample, and test sample. 

Other designations for samples are bulk sample, primary sample, secondary sample, subsample, laboratory sample, and test sample. These terms are used when a sample of a bulk system is divided, possibly a number of times, before actually being used in an analysis. For example, a water sample from a well may be collected in a large bottle (bulk sample or primary sample), from which a smaller sample is acquired by pouring into a vial to be taken into the laboratory (secondary sample, subsample, or laboratory sample), then poured into a beaker (another secondary sample or subsample), before a portion is finally carefully measured into a flask (test sample) and diluted to make the sample solution. 

Sample (subsamples) Accumulated Dose, AD (Gray) Weighted Mean Standard ESR Ages ... 

Documented testing procedures make the work in the laboratory controlled chemicals, reagents, samples, subsamples, analyses, and analysis results are traceable (chain-of-custody)... 

A few of the many manuals on chemical analysis which include instructions on sample collection may be mentioned. For over 100 years, AOAC INTERNATIONAL, has published detailed experimental procedures for sampling, subsampling and pretreatment of natural materials with the latest volume (Horwitz 2000) containing procedures for materials such as agricultural liming materials, fertilizers, plants, animal feed and dairy products in various chapters. A chapter on sampling dairy and related products is in the book edited by Marshall (1993) on Standard Methods for the Examination of Dairy Products. Specific sampling procedures for various food commodities are summarized by Ihnat (1982), based mostly on the AOAC manual. 

Illustration showing the method of coning and quartering as a means of reducing a gross sample for subsampling, (a) The gross sample is first piled into a cone and... 

Practical considerations enter into the experimental plan in various other ways. In many programs, variables are introduced at different operational levels. For example, in evaluating the effect of alloy composition, oven temperature, and varnish coat on tensile strength, it may be convenient to make a number of master alloys with each composition, spHt the alloys into separate parts to be subjected to different heat treatments, and then cut the treated samples into subsamples to which different coatings are appHed. Tensile strength measurements are then obtained on all coated subsamples. 

The standard way to proceed would be to fit the model to the data relative to each experimental unit, one at a time, thus obtaining a sample of parameter estimates, one for each experimental tumor observed. The sample mean and dispersion of these estimates would then constitute our estimate of the population mean and dispersion. By the same token, we could find the mean and dispersion in the Control and Treated subsamples. 

The literature on sampling bulk materials is more specific and more quantitative than the general discussion presented above. Nevertheless, experiments on the sampling and subsampling procedures... 

The test presented in the previous section is useful when a smaller probability of false detection is needed than is provided by the distribution-free test. However, the test in the previous section is no panacea. Reduction of the skewness through proper choice of sampling and subsampling procedures is an alternative that may have much more potential for improving the study. 

The objective of sediment and water sampling is to obtain reliable information about the behavior of agrochemicals applied to paddy fields. Errors or variability of results can occur randomly or be due to bias. The two major sources of variability are sediment body or water body variability and measurement variability . For the former, a statistical approach is required the latter can be divided into sampling variability, handling, shipping and preparation variability, subsampling variability, laboratory analysis variability, and between-batch variability. ... 

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