Precision in measurement

Hasegawa et al. [76] measured miconazole serum concentration by a high performance liquid chromatographic method. The authors assessed whether the internal standard method produced an intra-assay error and found that the method gave more precise and more reproducible results compared to the absorption calibration curve method. With 0.5 pg/mL of miconazole, the coefficient of variation produced by that method was 3.41%, whereas that of the absorption calibration curve method was 5.20%. The concentration of absorptions calibration curve method showed higher values than the internal standard method. This indicated that the internal standard method was far more precise in measuring the miconazole serum concentrations than the absorption calibration curve method. 

In the equation s is the measured dielectric constant and e0 the permittivity of the vacuum, M is the molar mass and p the molecular density, while Aa and A (po2) are the isotope effects on the polarizability and the square of the permanent dipole moment respectively. Unfortunately, because the isotope effects under discussion are small, and high precision in measurements of bulk phase polarization is difficult to achieve, this approach has fallen into disfavor and now is only rarely used. Polarizability isotope effects, Aa, are better determined by measuring the frequency dependence of the refractive index (see below), and isotope effects on permanent dipole moments with spectroscopic experiments. 

Determined to bring order to the chaotic systems of measurement then used in Russia, he used techniques developed abroad and invented some measuring devices himself. He established the metric system in Russia and insisted on a greater precision in measuring equipment. 

Multiplying Gauges To attain the requisite precision in measurement of small pressure differences by liquid-column manometers,... 

Strictly, there should be a correction for the effect of fringing but this is not normally considered significant. It is not usually possible to obtain very great precision in measurements of high resistivity and results are never quoted beyond two significant figures. Often, between sample variability is such that two materials would be considered really significantly different only if their resistivities differed by a factor of 10. 

C. Precision in Measurements of Activation Energies. The value of the activation energy E may be calculated from a knowledge of the specific rate constants at two different temperatures. By rearranging the Arrhenius equation we have... 

All the major manufacturers of viscometers and rheometers have Internet sites that illustrate and describe their products. In addition, many of the manufecturers are offering seminars on rheometers and rheology. Earlier lists of available models of rheometers and their manufacturers were given by Whorlow (1980), Mitchell (1984), and Ma and Barbosa-Canovas (1995). It is very important to focus on the proper design of a measurement geometry (e.g., cone-plate, concentric cylinder), precision in measurement of strain and/or shear rate, inertia of a measuring system and correction for it, as well as to verify that the assumptions made in deriving the applicable equations of shear rate have been satisfied and to ensure that the results provided by the manufecturer are indeed correct. 

We have shown, in later sections, how precise INS measurements of the DOS provide the most stringent means of testing the model potential functions that lie at the heart of any LD or MD simulation. In the last a few years, we have systematically studied the vibrational dynamics of a large verity of phases of ice using above instruments at ISIS. These spectra were obtained at very low temperatures (< 15 K) on the recoverable high-pressure phases of ice and a few forms of amorphous forms of ice, in order to reduce the Debye-Waller factor and avoid multiphonon excitations. Hence the one-phonon spectra, g(co), can be extracted from the experimental data for the theoretical simulations. 

A radioimmune assay for calcitonin has recently been developed (Dl), and this should give more precision in measuring calcitonin in blood. 

Overall the analytical precision in measurements made on the fish extract was acceptable. Because two fish extracts were supplied to participating laboratories, two separate measurements were made the average deviation fi om the mean (ADM) in the first instance was 10.2 while in the latter it was 16.2. The smaller ADM value was thought to be due to laboratories correcting for interferences from other co-eluting interferences. This was not performed in the latter case. 

Heydorn, K. (1976). Continuous quality control of analytical results from neutron activation analysis of air filter samples based on the analysis of precision, in Measurement, detection and control of environmental pollutants, p. 61, International Atomic Energy Agency, Vienna. 

Our aim instead was to devise an inexpensive and transportable system that could easily be assembled in the laboratory, and that might be dedicated to the quantitative study of a few selected anal)de species rather than the wide variety open to MMW spectrometry as a whole. In order to retain precision in measurement of sample signals, it would be necessary to deploy on-line computer control of the system as well as computer analysis of data. Allied to this it would be desirable to use a stand-alone mode of operation in which the measurements were made as insensitive as possible to design quirks, and to external environmental features such as temperature and pressure. 

Marshall, A. G. Chen, L. Cottrell, C. E. Limits to Precision in Measurement of Peak Height, Position, and Width in Fourier Transform Spectrometry No. 67, Dlv. Anal. Chem., Natl. Mtg. Am. Chem. Soc., Anaheim, CA, Sept. 10, 1986. 

The United States Natural Gas Industry s goal for precision in measurement of BTU is less than one BTU. The need for such extreme accuracy equal to 0.1% can be understood from the magnitude of United States natural gas consumption (Table 1). 

As a natural consequence when the commutator of two operators/ observables is non-zero, then the high precision in measuring one of it implies the infinite error in observing the eigen-values of the other. This is the case for the space and momentum operators on a certain direction that, while obeying the formal eigen-value problems... 

Because we cannot observe nature with complete certainty, we need to establish the types of uncertainty we encounter in making observations. To do this, two terms are used accuracy and precision. Although these words may be synonymous in everyday speech, each has its own meaning in scientific or engineering usage. Accuracy indicates how close the observed value is to the true value. Precision is the spread in values obtained from the measurement. A precise observation has several measurements close in value. Figure 1.7 illustrates the concepts of accuracy and precision in measurement and shows how the two terms differ. 

Another unit of pressure arises from the importance of the atmosphere. The average pressure at sea level is close to 760 torr. The common observation of an apparent average atmospheric pressure led to the definition of a unit called an atmosphere (atm), which was set equal to 760 torr. As science has become more precise in measuring it, this equivalence still remains ... 

X-ray diffraction as a method for investigating the levels of crystallinity in a polymer has been shown to be extremely precise in measuring differences in crystalline levels, but quantitative values cannot be assigned to the crystallinity by this method. The results are only relative to the samples tested or to empirically designated standard samples of crystallinity. The use of X-ray diffraction for the evaluation of crystallinity in polymers has three disadvantages for the average plastic fabricator and user ... 

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