Sample stratified

In this article, the complex cluster sampling, stratified sampling survey of RRT Warner model of binary choice sensitive question have been designed, and the estimate population proportion and estimated variance formula of RRT Warner model by cluster sampling and stratified sampling have been deduced meanwhile, combined with the survey example of premarital sex of college student in Soochow University, With high reliability, our survey methods on Warner model may have an extensive application in sensitive question survey. 

When the target population is segregated, or stratified, equation 7.5 provides a poor estimate of the amount of sample needed to achieve a desired relative standard deviation for sampling. A more appropriate relationship, which can be applied to both segregated and nonsegregated samples, has been proposed. ... 

How many samples are taken can be of importance. One sample often suffices where it is known that the material in question is homogeneous for the parameter(s) to be tested, such as for pure gases or bulk solvents. If this is not the case, then statistical sampling should be considered. Samples should be taken from various points within the material, if the material stratifies. 

Generally, Httle is known in advance concerning the degree of homogeneity of most sampled systems. Uniformity, rarely constant throughout bulk systems, is often nonrandom. During the production of thousands of tons of material, size and shape distribution, surface and bulk composition, density, moisture, etc, can vary. Thus, in any bulk container, the product may be stratified into zones of variable properties. In gas and Hquid systems, particulates segregate and concentrate in specific locations in the container as the result of sedimentation (qv) or flotation (qv) processes. 

In a top-feed filter test, the filter cake will contain all of the solids, provided they are all emptied from the sample container. The danger in this type of test is that the solids will stratify, particularly if the c e formation time is prolonged. Close examination of the filter cake will... 

The aims of sampling are to establish whether eontaminants are present, their distribution and eoneentrations. Commonly-used sampling regimes inelude square grid, stratified random or simple random teehniques. Evenly-spaeed sampling points may be appropriate if the eontamination is visible otherwise judgement is required based on whether the land slopes or is flat. Samples are also taken near to the point of release. 

Is it possible to stratify the sampling region in such a way as to reduce the spatial variations within strata ... 

Analysis and Interpretation of the Information and data resulting from the exploratory study will provide the basis for designing the final definitive monitoring study Including all elements of the QA/QC plan. For example, decisions must be made on whether or not the selected control area Is adequate and appropriate whether the hypothesized model Is valid whether the study area should be stratified and If so, how what number of samples should be collected at what locations and whether or not the QA/QC plan for sampling is adequate and if not, how it should be changed. 

Danz NP, Regal RR, Niemi GJ, Brady VJ, Hollenhorst T, Johnson LB, Host GE, Hanowski JM, Johnston CA, Brown T, Kingston J, Kelly JR. 2005. Environmentally stratified sampling design for the development of Great Lakes environmental indicators. Environ Monitor Assess 102 41-65. 

In the squamous/stratified epithelium covering, the palatal aperture of the N-P canals and the dorso-lateral surfaces of the papilla, there are occasional clusters of taste buds. These non-olfactory chemosensory elements are positioned at or near to the entrance to the AOS, suggesting that some initial chemosensation may arise from the sampling of material... 

During re-entry, stratified whole-leaf sampling was conducted. Twenty-four leaves from the harvesting zone of the crop were collected in a 500-mL polyethylene bottle in duplicate. Leaf samples were stored at 4 to 7°C in the laboratory until analysis. After analysis, the leaf volume was measured by stereometric volumetry using a method described by Sherle (1970). A linear relationship between leaf volume and leaf area was determined for carnation leafs by measuring leaf area (one-sided) with a LI-COR 3100 (Ll-Cor, Inc. Nebraska). 

Ottaway, J. H. and M. R. Mathews (1988), Trace element analysis of soil samples from a stratified archaeological site, Environ. Geochem. Health 10,105-112. 

Fig. 2.11. Schematic representation of a parallel tempering simulation, in which the N states of a stratified FEP calculation are run concurrently. After a predefined number of steps, iVSampie, the cells are swapped randomly across the different processors. A Metropolis-based acceptance criterion is used to determine which of the N / 2 exchanged A-states should be accepted. Pairs of boxes that fail the test are swapped back. Then additional sampling is performed until the next exchange of the replicas...

Furthermore, the exposure data should be obtained by stratified random sampling of houses based on population registers and data on building stock. 

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