Randomization technique

The aims of sampling are to establish whether contaminants are present, their distribution and concentrations. Commonly-used sampling regimes include square grid, stratified random or simple random techniques. Evenly-spaced sampling points may be appropriate if the contamination 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. 

Therefore, sampling correctness has a special meaning in Gy s theory. When we talk about a correct sample, we mean that the principle of correct sampling has been followed. Note that correctness is a process, which we have some control over. We do not have control, however, over the accuracy of a sample value, which is a result. This is no different than SRS, where we can control the method by which we obtain a subset of the population of individual units using a random technique. But we are stuck with the resulting sample and its value of the characteristic of interest. 

Distance geometry is, at heart, a random technique. It is therefore usual to generate more than one conformation in order to try to explore the conformational space that is consistent with the experimentally derived distances. The resulting set of structures is often displayed as a superimposed set this enables the similarities and differences between the structures to be easily identified. For example, in Figxrre 9.18 (colour plate section) we show an ensemble of conformations of RANTES, a small protein called a chemokine that is impUcated in inflammation [Chung et al. 1995]. It is often found that some parts of the molecule adopt very similar conformations in all the structures whereas other regions show considerable variation. This is often interpreted as an indication of conformational flexibility, but it is important to remember that it may also indicate a lack of experimental data for those atoms. 

Concluding Comments. Extensive fundamental research into further development of catalysts has been supported by the use of theoretical chemistry and modem mathematical methods based on random techniques. The plants in which these results have been realized since 1989 operate in the Leverkusen works. 

Of course, if accounts for a very small fraction of ABCD, the random technique becomes increasingly wasteful. Imagine that the function F x,y) is nonzero over less than 1% of the total area ABCD. Then, on the average, 99 out of 100 shots will contribute zeroes to the average, and only one out of a hundred will deliver a nontrivial contribution. 

De la RosaFox N., Esquivias. L, Villares R, and Jimenez-Garay R., Structural models of the amorphous alloy Ge0.20As0.40Se0.40 by a random technique, Phys. Rev. B, 33,4094-4099 (1986). 

Specimen sampling procedures, including randomization techniques (for control of bias), methods and equipment to be used ... 

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