[en] total error ; uncertainty ; systematic error ; random error ; validation ; results quality
[en] The guidelines ISO 17025 and ISO 15189 aim at improving the quality assurance scheme of laboratories. Reliable analytical results are of core importance due to the critical decisions that are taken with them. Therefore among other topics, these documents require that analytical methods be validated and that laboratories should be able to provide measurement uncertainty of their measured routine results. To evaluate analytical methods fitness of purpose, total error has been and is more and more applied to assess reliability of results generated by analytical methods. However, the ISO requirement to estimate measurement uncertainty seems in opposition with the total error concept, leading to delays in their implementation by laboratories and increased confusion for the analysts. Thus, this article aims at clarifying the divergences between total error and measurement uncertainty, but also to discuss their main similarities and give some emphasise to their implementations.