Random_and_Systematic_Effects_TimelineIn a recent edition of the premier journal devoted to quality and metrology in chemistry Accreditation and Quality Assurance Ivo Leito has attempted to express in very simple terms the essence of Metrology in Chemistry. In the article Accred. Qual. Assur. 2015, 20, 229–231 he arrived at three main recommendations:

1. Whenever possible, comparisons with reference values should be carried out. The reference values can be realized in different ways: Certified reference materials (CRMs), Laboratory reference materials (LRMs), Measurements with reference methods, etc.

2. Data on stable samples should be collected over long time periods (e.g. as the X chart), in order to evaluate as many sources of variability in the analysis method, as possible. The longer the time period, the more systematic effects will become random and thus easier to evaluate (more on this topic can be found in a recent review on bias).

3. “Do not stop there!”, meaning that the above mentioned activities should run in a lab on a continuous basis.

As a conclusion, it can be said that constant improvement is the key to reliable analytical results.


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