Statistical significance, number

The results of two field experiments involving a statistically significant number of wells indicated that quaternary ammonium salt polymers can function well as swelling clay and mineral fine particle stabilizers under actual field conditions. 

As with all research involving humans and other intelligent creatures, it is also essential to design the experiments to avoid the introduction of unintentional bias from over-helpful subjects. We should remember the example of geneticist Mendel and his overly helpful fellow monks, who quietly weeded the pea patch so that the results came out in line with Mendel s predictions. Thus, where appropriate, variants on the double-bfind principle should be apphed in experimental design, and statistically significant numbers of measurements need to be made to properly account for the inherent variability of living subjects. 

If a certain analysis is frequently carried out, it may be advantageous to keep in stock some well-mixed bulk samples (low, medium and high range values), sub-samples of which should be included with every fresh batch of analyses, and again well-mixed before weighing. After a statistically significant number of analyses, an accepted average value for the bulk sample is obtained, and the amount of scatter of results computed as a standard deviation, s, where... 

Imide passivated linear devices was determined from I-V characteristics of statistically significant numbers of devices following severe PTHB test (i.e., 15 psi, 120°C, 100% relative hvimidity, and 30 V bias). Two coat (3 p) polyimide passivation provided almost twice the mean time to failure of 1 p thick PSG passivation. Polyimide protection against high humidity (13,14) and Na" " diffusion (15) has been reported previously. 

After incubation, the spontaneous his - his + reversions found on background Plate C are subtracted from the colony count on Test Plate B. If a statistically significant number of colonies remain (i.e., net revertants ), the POM sample contains one or more chemicals that are promutagens. Sam-... 

Retrospective validation or qualification is discouraged, but may be applicable in some situations, where a statistically significant number of batches with consistent formulas, procedures and analytical methods are available. Sufficiently detailed past processing and control records must be available for retrospective validation studies to be considered. 

Future authenticity testing of cocoa butter and chocolate products is likely to follow defined paths. To assure the authenticity of cocoa butters databases of the composition of the relevant fats will be required, constructed from a statistically significantly number of samples of proven provenance and processing history. Analyses must be carried out using internationally validated methods and characterized reference materials by a number of respected laboratories. Scientific co-operation within the European Union is beginning to develop such approaches in ensuring the authenticity of other foods such as olive oil. 

The difference in radioactivity between the protein and dialyzing compartments was used as a measure of bound acetyl glutamate (30) in one case, for example, it was determined that 100 counts had bound, with a standard deviation of 20. It appears that a statistically significant number of experiments is required to ascertain the binding of acetyl glutamate, in view of the small magnitudes and large experimental errors involved. 

Consider, for example, a vessel that contains a statistically significant number of molecules, such as a mole of helium atoms at room temperature. With a high degree of probability bordering on certainty, this ensemble is asymmetric at any instant in time because, a priori, any system is expected to be asymmetric unless constrained to be otherwise, and no such... 

Precision refers to the degree of repeatability under the stated conditions of the method. It is expressed as percent relative standard deviation (% RSD) for a statistically significant number of analyses of samples. Precision provides a measure of day to day, analyst to analyst and instrument to instrument variation on a routine basis. The precision data provided in support are standard deviation, % RSD, confidence intervals and may also include inter laboratory variations. 

The assay system described in the present study should be useful in screening potential metal carcinogens for their ability to induce transformation. However, further work is required to demonstrate and validate that each of the various metals induce neoplastic transformation in tissue culture. A statistically significant number of transformed colonies induced by exposure of cells to each of the metal compounds must be cloned and derived into cell lines. The tumorigenic potency of these various cell lines must be tested in nude mice. 

A statistically significant number of blank measurements are made. Although at least 10 and as many as 20 rephcates have been recommended, 16 measurements are generally selected. 

Inhalation exposure to acetaldehyde has produced nasal tumors in rats and laryngeal tumors in hamsters. Male and female rats were exposed to acetaldehyde 6hday , 5 day week for 28 months at concentrations of 0, 750, 1500, or 3000 ppm. A concentration-related incidence of squamous cell carcinomas of the respiratory epithelium was observed in both male and female rats. A statistically significant number of adenocarcinomas occurred in the olfactory epithelium of both sexes of rats exposed at all three acetaldehyde concentrations. Male and female hamsters were exposed to acetaldehyde 7hday, 5 day week at concentrations gradually reduced from 2500 to 1650 ppm for 52 weeks. Both sexes of acetaldehyde-exposed hamsters developed laryngeal tumors consisting of squamous cell carcinomas and adenosquamous cell carcinomas. 

A factorial design of kinetic experiments utilizing Au/TS-1 was the first study of propylene epoxidation kinetics in the absence of catalyst deactivation [55]. The adoption of a factorial design allowed for the examination of the largest statistically significant number of reaction conditions centered around the standard reaction mixture of 10/10/10/70 vol% Fl2/02/propylene/diluent while avoiding flammable conditions. The experimental results [55] from the evaluation of three Au/TS-1 catalysts showed that PO production could be approximated using the power rate law expression rpo = k [Fl2] [O2] [CsHe]... 

Simulations of copper electrodeposition in sub-micron features in the presence of a leveling agent indicate that the formation of void-free deposits requires tight control of the operating conditions. For very small features, primarily one dimensionless group (equation 7) dictates the leveling capability of a process. Results also indicate that as feature size is reduced, the deposition tends to become conformal unless the additive chemistry is modified. It is proposed that conformal deposit is not desirable because random variations in deposition rate will lead to void formation in a statistically significant number of features on a wafer. 

Despite a massive number of publications reporting the use of AC in poisoning treatment, there is a lack of systematic comprehensive clinical studies which should have involved a randomised statistically significant number of patients in several clinical centres. The usefulness of AC in poisoning treatment has never been proven or questioned ever since, and the attitixle of clinicians to this subject seems to be ambivalent. The general perception is that administration of AC is beneficial to the patient as it adsorbs the toxic substance and reduces its concentration in the body. Some authors, however, argue that despite this reduction, it has never been proven that administration of AC actually improves the clinical outcome [24J. 

The CSD (April 1997, version 6.2,167,797 entries) contains accurate crystal structure data for organic, inorganic and organometallic compounds [36]. The retrieval of geometrical data from the CSD and its subsequent analysis by statistical procedures allows for extremely reliable conclusions pertaining to the nature of intermolecular interactions. Only conclusions based on examination of a statistically significant number of crystal structures are chemically mean-... 

---