Theory and Practice of Ensuring the Validity in Testing Laboratories

The features of the organization of ensuring the validity in testing laboratories are investigated. Measures to ensure the validity of the results depending on modern quality concepts are analyzed. The author shows the necessity of building a systematic model of ensuring the validity to achieve a balance between the customer's expectations regarding quality and the laboratories’ quality statement and quality concept. The processes in the laboratory were analyzed in terms of the requirements of the ISO 17025 standard and the developed system model for ensuring reliability. The standards that allow applying qualitative and quantitative methods of validity assurance are considered. Examples of practical assurance measures for processes are given: equipment and personnel management facilities, deviation from the contract, externally provided products, LIMS, impartiality, sampling, risk management, management reviews, and improvement. The role of method validation to ensure validity is defined. The uncertainty of the result is considered as one of the options for generalizing the quantitative indicator of validity. Among the main disadvantages of quantitative methods are the insufficient power of classical criteria for small sample sizes and when the Gaussian distribution law is violated. The features of the implementation of methods for ensuring higher levels of validity are investigated. The algorithm of actions to improve the reliability of test results depending on the identified risks, available financial and human resources, and adopted quality goals, is shown.