Accuracy Type 1 error

In modem approaches to drug discovery there are numerous approximations, assumptions and accuracy or error limitations. Inevitably, this affects the reliability of the data, information and knowledge with the obvious implication that some of the knowledge will be incorrect. Appreciating the differences between the types of parameters can help to ensure that when possible the appropriate statistical techniques are used and that the reliability of knowledge is considered when making important decisions. 

SD itself does not yield useful information, unless compared to the mean (%CV Section 15.1). Between-assay variation is generally greater than within-assay variation, but care should be taken with the latter to reduce bias by randomly distributing the duplicates. The between-assay variation is usually of more value to estimate the accuracy of the procedure and, plotted on a quality-control chart, may indicate trends, such as deterioration of reagents (bias-type error Section 1.3). An example of the calculation of the within-assay and between-assay variability is given in Table 15.3. In this example, the SD of between-assay results is about 5-6 times higher than for the within-assay results. For a satisfactory EIA, this factor should be less than 2-3 and the between-assay variability should be less than 10%. 

After the unexpected demise of one of the authors. Prof. Dr. Heinz Mauser, on October 4, 1995, before completion of the final version of the manuscript, the task to finish the book for publication fell upon me. A major difficulty in this process was checking the large number of equations for consistency and accuracy, however. I have to thank many of my graduate students who helped me to check the manuscript for typing errors and inconsistency. I want to thank especially Mrs. Dipl.-phys Albrecht KJotz, Dipl.-phys. Matthias Rothmund, and Dipl.-inf. Fred Rapp. The latter was very much involved in programming a new workstation version of the photoki-netic evaluation program. 

The parameters in the original parameterization are adjusted in order to reproduce the correct results. These results are generally molecular geometries and energy differences. They may be obtained from various types of experimental results or ah initio calculations. The sources of these correct results can also be a source of error. Ah initio results are only correct to some degree of accuracy. Likewise, crystal structures are influenced by crystal-packing forces. 

Every effort has been made to select the most reliable information and to record it with accuracy. Many years of occupation with this type of work bring a realization of the opportunities for the occurrence of errors, and while every endeavor has been made to prevent them, yet it would be remarkable if the attempts towards this end had always been successful. In this connection it is desired to express appreciation to those who in the past have called attention to errors, and it will be appreciated if this be done again with the present compilation for the publishers have given their assurance that no expense will be spared in making the necessary changes in subsequent printings. 

Accuracy Under normal conditions relative errors of 1-5% are easily obtained with UV/Vis absorption. Accuracy is usually limited by the quality of the blank. Examples of the type of problems that may be encountered include the presence of particulates in a sample that scatter radiation and interferents that react with analytical reagents. In the latter case the interferant may react to form an absorbing species, giving rise to a positive determinate error. Interferents also may prevent the analyte from reacting, leading to a negative determinate error. With care, it maybe possible to improve the accuracy of an analysis by as much as an order of magnitude. 

The accuracy achievable by the ratio method amounts to approximately 5-10 atom% when ionization edges of the same type are used, i. e. only K edges or only L edges, whereas the error in quantification increases to +15-20 atom% for the use of dissimilar edges. Improvement of the quantification accuracy up to approximately 1 atom% is possible if standards are used. 

The accuracy of MWD directional measurements is generally much better than the single- or multishot-type measurements since the sensors are more advanced and the measurements more numerous. The azimuth measurement is made with the three components of the earth magnetic field vector and only with the horizontal component in the case of the single shot or multishot. The accelerometer measurements of the inclination are also more accurate whatever the value of the inclination. The average error in the horizontal position varies from... 

Voltage transformers are classified into types AL, A, B, C and D, in descending order of accuracy. The ratio errors for small voltage changes (within ( 10 per cent of the rating) vary between 0.25 per cent and 5 per cent and the phase errors between ( 10 minutes and ( 60 minutes. 

Ratio and phase angle errors also occur due to the need for a portion of the primary current to magnetize the core and the requirement for a finite voltage to drive the current through the burden. These errors must be small. Current transformers are classified (in descending order of accuracy) into types AT, AM, BM, C and D. Ratio errors in class AT must be within the limits of ( 0.1 per cent for AT and ( 5 per cent for D, while the phase error limit on class A1 is ( 5 minutes to ( 2 minutes in types CM and C. 

Our little table of accuracy shows that, in the Hartree scheme, there is a certain balance between the correlation errors for the two spin types which, in some cases, may lead to a cancellation of these errors with good theoretical results as a consequence. After the introduction of exchange, this balance is gone and, if the correlation between electrons with opposite spins is not taken into proper account, the final results may be influenced by this large... 

It is important to understand that this material will not be presented in a theoretical vacuum. Instead, it will be presented in a particular context, consistent with the majority of the author s experience, namely the development of calibrations in an industrial setting. We will focus on working with the types of data, noise, nonlinearities, and other sources of error, as well as the requirements for accuracy, reliability, and robustness typically encountered in industrial analytical laboratories and process analyzers. Since some of the advantages, tradeoffs, and limitations of these methods can be data and/or application dependent, the guidance In this book may sometimes differ from the guidance offered in the general literature. 

A fully automated instrumental procedure has been developed for analyzing residual corrosion inhibitors in production waters in the field. The method uses ultraviolet (UV) and fluorescence spectrophotometric techniques to characterize different types of corrosion inhibitors. Laboratory evaluations showed that fluorescence is more suitable for field application because errors from high salinity, contamination, and matrix effect are minimized in fluorescence analysis. Comparison of the automated fluorescence technique with the classic extraction-dye transfer technique showed definite advantages of the former with respect to ease, speed, accuracy, and precision [1658],... 

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