Absolute bias

The issues of relative bias or absolute bias also need consideration. Relative bias is likely to involve comparisons of gross sample results, whereas absolute bias is based on comparison with bias-free reference values and usually involves increment-by-increment comparisons. 

VS data are used to select the regression model and curve fitting. The regression model and weighting that generate the lowest total error (Absolute Bias + Intermediate Precision) of the VS should be chosen. 

Table n gives a comparison of the measured and calculated temperature coefficients and eigenvalues between 74 and 464 F. The temperature defect between 74° and 464 F was estimated from integrated rod worths to be about 3%. Rod worths and temperature coefficients were b d on a calci ted effective delayed neutron fraction fi of 0.0074 (i.e., p/p = 1.16). In addition to having a small absolute bias (all calculated eigenvalues are within + 0.5 and - 0.9% of measured values), the model describes the temperature effects quite accurately. 

Absolute Bias—Due to the use of total immersion thermometers or temperature sensing systems designed to emulate them, the distillation temperatures in this test method are somewhat lower than the true temperature. The amount of absolute bias has not been determined. 

Absolute Bias—Since there is no accepted reference material suitable for determining the bias for this test method, bias cannot be determined. The amount of bias between this test vapor pressure and true vapor pressure is unknown. 

Correlation Average Deviation Absolute Average Deviation Bias Maximum Deviation... 

In the presented range of pressure variation. Hamers [163] also has studied the influence of the substrate temperature on the plasma and the material. It was found that in the temperature range of 200 to 300°C the trends of the bias voltage, the plasma potential, and the growth rate as functions of pressure all are the same, while the absolute magnitude depends on the temperature. The trends in material properties are similar to the ones reported above at a temperature of 200°C the material quality is worse than at higher temperatures. The a-y transition occurs at a lower pressure than at a temperature of 250°C. This has been observed before [248]. 

Accuracy (systematic error or bias) expresses the closeness of the measured value to the true or actual value. Accuracy is usually expressed as the percentage recovery of added analyte. Acceptable average analyte recovery for determinative procedures is 80-110% for a tolerance of > 100 p-g kg and 60-110% is acceptable for a tolerance of < 100 p-g kg Correction factors are not allowed. Methods utilizing internal standards may have lower analyte absolute recovery values. Internal standard suitability needs to be verified by showing that the extraction efficiencies and response factors of the internal standard are similar to those of the analyte over the entire concentration range. The analyst should be aware that in residue analysis the recovery of the fortified marker residue from the control matrix might not be similar to the recovery from an incurred marker residue. 

The overall bias of the calculation is the sum of those for each stage (absolute value) and the overall variance is given as... 

The fundamental figure of merit for rectification, the rectification ratio, RR, is defined as the current at a positive bias V divided by the absolute value of the current at the corresponding negative bias —V RR = I(V)/ /(—V) I. Commercial doped Si, Ge, or GaAs pn junction rectifiers have RR between 10 and 100. 

When the sample is biased positively (Ub > 0) with respect to the tip, as in Fig. 9c, and assuming that the molecular potential is essentially that of the substrate [85], only the normal elastic current flows at low bias (<1.5 V). As the bias increases, electrons at the Fermi surface of the tip approach, and eventually surpass, the absolute energy of an unoccupied molecular orbital (the LUMO at +1.78 V in Fig. 9c). OMT through the LUMO at — 1.78 V below the vacuum level produces a peak in dl/dV, seen in the actual STM based OMTS data for nickel(II) octaethyl-porphyrin (NiOEP). If the bias is increased further, higher unoccupied orbitals produce additional peaks in the OMTS. Thus, the positive sample bias portion of the OMTS is associated with electron affinity levels (transient reductions). In reverse (opposite) bias, as in Fig. 9b, the LUMO never comes into resonance with the Fermi energy, and no peak due to unoccupied orbitals is seen. However, occupied orbitals are probed in reverse bias. In the NiOEP case, the HOMO at... 

The bias-correction is necessary to correct both the absolute magnitude and the seasonal cycle to that of the observations. This approach assumes that the same model biases persist in the future climate and thus GCMs more accurately simulate relative change than absolute values. It provides a correction of monthly mean climate only and does not correct biases in higher order statistics including the simulation of extreme events and persistence. 

Accelerated solvent extraction (ASE), capillary chromatography sample preparation, 4 609, 610 Accelerated temperature, humidity, and bias (THB) tests, 10 9 Accelerated weathering tests, 19 584 Acceleration, exponents of dimensions in absolute, gravitational, and engineering systems, <5 584t Accelerators, 9 554-555 10 411, 713 22 61 23 861-862 for cement, 5 485... 

The behavior of the detection algorithm is illustrated by adding a bias to some of the measurements. Curves A, B, C, and D of Fig. 3 illustrate the absolute values of the innovation sequences, showing the simulated error at different times and for different measurements. These errors can be easily recognized in curve E when the chi-square test is applied to the whole innovation vector (n = 4 and a = 0.01). Finally, curves F,G,H, and I display the ratio between the critical value of the test statistic, r, and the chi-value that arises from the source when the variance of the ith innovation (suspected to be at fault) has been substantially increased. This ratio, which is approximately equal to 1 under no-fault conditions, rises sharply when the discarded innovation is the one at fault. 

The use of bromcresol green for the measurement of albumin has been criticized on several counts. There is a tendency for the protein-dye complexes to precipitate at pH 4.2, which is very near the iso-ionic pH of albumin. It is claimed that the method is not absolutely specific for albumin and particularly with serum samples shows a positive bias in results. There is also some variability in the intensity of the colour produced with albumins from different sources, a fact which makes the choice of the standard material important. 

NIST SRM-979 is a high purity Cr(N03)3 9H20 crystalline sohd sold as an isotopic reference material. It was prepared from a commercial material and its isotopic composition was analyzed by TIMS, along with gravimetric mixtures of purified isotopes to examine instrumental bias (Sheilds et al. 1966). The absolute ratio is reported as 0.11339, with... 

The accuracy of a test is a measure of how close the test result will be to the true value of the property beiug measured (ASTM, 2004 Patuaik, 2004). As such, the accuracy cau be expressed as the bias betweeu the test result aud the true value. However, the absolute accuracy cau be established ouly if the true value is kuowu. 

As noted in the last section, the correct answer to an analysis is usually not known in advance. So the key question becomes How can a laboratory be absolutely sure that the result it is reporting is accurate First, the bias, if any, of a method must be determined and the method must be validated as mentioned in the last section (see also Section 5.6). Besides periodically checking to be sure that all instruments and measuring devices are calibrated and functioning properly, and besides assuring that the sample on which the work was performed truly represents the entire bulk system (in other words, besides making certain the work performed is free of avoidable error), the analyst relies on the precision of a series of measurements or analysis results to be the indicator of accuracy. If a series of tests all provide the same or nearly the same result, and that result is free of bias or compensated for bias, it is taken to be an accurate answer. Obviously, what degree of precision is required and how to deal with the data in order to have the confidence that is needed or wanted are important questions. The answer lies in the use of statistics. Statistical methods take a look at the series of measurements that are the data, provide some mathematical indication of the precision, and reject or retain outliers, or suspect data values, based on predetermined limits. 

A comparison of the theory with experiments is shown in Fig. 5.8. For Al(l 11), a = 2.88 A, 4) = 3.5 eV, it follows that k = 0.96 A" y = 3.48 A. The slope of the In Az z curve from Equations (5.49) through (5.51) fits well with experimental data. The absolute tip-sample distance is obtained from curve fitting, which gives the shortest average tip-sample distance at / = 40 nA (with bias 50 mV) to be about 2.9 A, consistent with the measured tip-sample distance (Diirig et al, 1986, 1988), about 1 A before mechanical contact. 

It is seen from Fig. 11.1 that, beyond any bias from the personal choice of the examples, the isoprenoids show the largest skeletal variety in all ecosystems. The absolute maximum is observed for the isoprenoids from the Indo-Pacific (dark green ribbon, sixth from the right), which represents a triunqjh of the natural product diversity of Indo-Pacific coral reefs. To its left, the pale violet ribbon for the Caribbeans shows a similar trend, although with lower values attributable to the more restricted area with less extensive and varied coral reefs. 

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