Intrinsic error

In the previous chapter, a comprehensive description was provided, from four complementary perspectives, of the process of how human errors arise during the tasks typically carried out in the chemical process industry (CPI). In other words, the primary concern was with the process of error causation. In this chapter the emphasis will be on the why of error causation. In terms of the system-induced error model presented in Chapter 1, errors can be seen as arising from the conjunction of an error inducing environment, the intrinsic error tendencies of the human and some initiating event which triggers the error sequence from this imstable situation (see Figure 1.5, Chapter 1). This error sequence may then go on to lead to an accident if no barrier or recovery process intervenes. Chapter 2 describes in detail the characteristics of the basic human error tendencies. Chapter 3 describes factors which combine with these tendencies to create the error-likely situation. These factors are called performance-influencing factors or PIFs. 

Several algorithms are available for the analysis of MS/MS spectra including SEQUEST, MASCOT, and X Tandem among others. Note that additional secondary quality control of assessment of MS/MS data has recently been implemented to assess identification probabilities and false positivity rates. The MS/MS spectra from an experiment can be interrogated against a concatenated forward and reverse database and an assessment of the intrinsic error rate of the data set can be made. Other approaches for secondary analysis of matching scores for peptide sequencing data include XCorr score normalization routines that are independent of peptide and database size.33... 

D. Feller and K. A. Peterson,/. Chem. Phys., 108, 154 (1998). An Examination of Intrinsic Errors in Electronic Structure Methods Using the Environmental Molecular Sciences Laboratory Computational Results Database and the Gaussian-2 Set. 

Ans. The percentage of copper, 86%, is close and appears to be within the intrinsic error of measurement and calculation, but may not be conclusive. 

As discussed above, an intrinsic error can result from using D50S to infer size distributions from the impactor data. Depending on the sampling conditions and on the chemical and physical properties of the aerosol sampled, each of the other errors can also be significant, and generally must be considered in sampling coal combustion aerosols. 

Denominators in both components are related to the number of phonons of Ep energy according to the Bose-Einstein statistics [21], Therefore the approximate method for bandgap determination in the case of indirect semiconductors has an intrinsic error of the order of Ep (see Figure 7.7b). 

The errors due to the mass spectrometer are also numerous, such as the variation in the source conditions and the instability of the mass scale. For statistical reasons, every measurement of a signal intensity carries a minimal intrinsic error. This error is inversely proportional to the square root of the number of ions detected for that signal. In order to optimize the reproducibility or the precision of the measurements, a maximum number of ions must thus be detected for every ionic species. 

All of these error sources, other than the minimal intrinsic error, can be reduced by using the internal standard method. The absolute measurement of the signal is replaced by the measurement of the signal ratio for the molecule that is measured and for the internal standard. The same compound can play the role of the internal standard for the quantification of various compounds within the mixture. 

This method is based on a comparison of the intensities of the signal corresponding to the product that has to be quantified with the one of a reference compound called the internal standard. This method allows the elimination of various error sources other than the minimal intrinsic error due to statistical reasons. In fact, if we choose as an internal standard a molecule with chemical and physical properties as close as possible to the properties of the molecule to be measured, the latter and the internal standard undergo the same loss in the extraction steps and in the derivative or the same errors in the introduction of the sample into the mass spectrometer, when the source conditions are varied. As both... 

Since one is interested, in the flrst instance, in linear response, there is no intrinsic error in using first-order quantum-mechanical perturbation... 

Error-prone PCR uses altered reaction conditions in order to increase the rate of production of copying errors. Taq-polymerase, when used in vitro, has an intrinsic error rate of about one noncomplementary nucleotide for every 10,000-100,000 bases (an error rate of 1 in 104 or 10s). In Table 8.2, conditions are described to increase the rate of mutations, where the error rate is increased by increasing the concentration of divalent cations (Mg2+ or Mn2+) and using increasingly unbalanced initial concentrations of nucleotides. Note that the error rate is tuned to between 2 and 15 errors for every 1000 base pairs, an increase of one to three orders of magnitude over the in vitro Taq-polymerase mutation rate. 

The uncertainty of commercial calibration gas mixtures is typically 1% of the amount fraction, and the contribution of this to the overall measurement uncertainty is much greater than the intrinsic error of the oxygen sensor for amount fractions of oxygen that are 0.1 ppm and above [2]. Consequently, test procedures that require calibrated gas mixtures will be limited by the uncertainty of those gas mixtures, and therefore carmot be used to test the accuracy of oxygen and other zirconia-based gas sensors, assuming the uncertainty of the sensor calibration is no worse than that of the test mixtures. At present, the uncertainty of commercial calibration gas mixtures is a limitation to verifying the accuracy of these gas sensors. 

Devos, D., and A. Valencia. 2001. Intrinsic errors in genome annotation. Trends Genet 17 429-31. 

We have only concentrated on relativistic density functional calculations on heavy-element compounds. Calculations on compounds of light elements have been reported in Refs. [157-159] and primarily aimed at high numerical accuracy. However, for these compounds the intrinsic error of existing density functional treatments is probably much larger than the relativistic effects, so the purpose of such calculations remains unclear. 

Figure 5.6b The worksheet for the calculation of the two-electron repulsion term, equation 5.52. The values, calculated in column R, follow from the intrinsic Error function defined in the Engineering function library in EXCEL.

The sonrces of errors (SE) in deconvolution may be classified as intrinsic errors and methodological errors, with the latter type of errors divided into experimental errors and data analysis errors. 

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