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Quality of products and services has encompassed more and more areas of society, such as foods and drugs, environment, health, safety of the working population, and many others. According to DIN ISO 8402 [1], quality is “the totality of features and characteristics of product or service that bear on its ability to satisfy stated or implied needs”, and the assurance of quality is defined...
Even under constant experimental conditions (same operator, same tools, and same laboratory, short time intervals between the measurements), repeated measurements of series of identical samples always lead to results which differ among themselves and from the true value of the sample. Therefore, quantitative measurements cannot be reproduced with absolute reliability.
Besides the validity of the analytical methods, controlled by internal and external tests, as well as proper training of the analysts, the reliability of all the instruments used for experiments and measurements provides the fundamentals of analytical quality assurance. There are therefore regulatory agency requirements for the qualification, calibration, and verification of analytical instruments.
Analytical results obtained for customers are usually the basis for correct decisions: for example, when looking at allowable concentration limits. But all measurements are affected by a certain error. Which error should be used as the basis of the decision?
Chronologically, the selection and development of an appropriate analytical method for a specific analytical purpose is the first stage in the validation of a method which should be capable of producing results that are fit for a particular purpose. However, method development is a wide field with specific investigations for each method, and therefore in this book only some aspects of selected analytical...
In interlaboratory studies, which are usually organized by a reference laboratory (“the organizer”), the participating laboratories receive part of a homogeneous bulk material which must be analyzed according to a given protocol. The results obtained are returned to the reference laboratory which evaluates the results and gives feedback to the participating laboratories.
Whereas the term “quality assurance” (QA) involves the overall measures taken by the laboratory to regulate quality, “quality control” (QC) relates to the individual measurements of samples. The two aspects of QC concern internal quality control, the subject of this chapter, and proficiency testing, which is a form of the external QC described in the next chapter.
Hypothesis testing is a very important part of statistics, and can be used to investigate whether the mean values of two or more series of measurement are equal, whether the variances of two or more data sets are identical, etc.
Correlation and regression analysis investigate the relationships between associated variables, but with different objectives depending on the nature of the variables.
Working in the lab, but unsure what your results actually mean? Would you like to know how to apply trueness tests, calculate standard deviations, estimate measurement uncertainties or test for linearity? This book offers you a problem-based approach to analytical quality assurance (AQA). After a short introduction into required fundamentals, various topics such as statistical tests, linear regression...
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