Coefficient de variation

Résumé

vignette|CV (coefficient de variation) = l'écart-type sur la moyenne En théorie des probabilités et statistiques, le coefficient de variation également nommé écart type relatif, est une mesure de dispersion relative. Le RSD (relative standard deviation en anglais) est défini comme la valeur absolue du coefficient de variation et est souvent exprimé en pourcentage. Définitions Le coefficient de variation est défini comme le rapport entre l'écart-type \ \sigma et la moyenne \ \mu : :CV = {\sigma \over \mu } Comparaison avec l'écart type Avantages

L'écart-type seul ne permet le plus souvent pas de juger de la dispersion des valeurs autour de la moyenne. Si par exemple une distribution a une moyenne de 10 et un écart-type de 1 (CV de 10 %), elle sera beaucoup plus dispersée qu'une distribution de moyenne 1000 et d'écart-type 10 (CV de 1 %).
Ce nombre est sans unité, c'est une des raisons pour lesquelles il es

Source officielle

https://fr.wikipedia.org/wiki/Coefficient_de_variation

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Smart monitoring has been studied and developed in recent years to create faster, cheaper, and more user-friendly on-site methods. The present study describes an innovative technology for investigative monitoring of heavy metal pollution (Cu and Pb) in surface water. It is composed of an autonomous surface vehicle capable of semiautonomous driving and equipped with a microfluidic device for detection of heavy metals. Detection is based on the method of square wave anodic stripping voltammetry using carbon-based screen-printed electrodes (SPEs). The focus of this work was to validate the ability of the integrated system to perform on-site detection of heavy metal pollution plumes in river catchments. This scenario was simulated in laboratory experiments. The main performance characteristics of the system, which was evaluated based on ISO 15839 were measurement bias (Pb 75%, Cu 65%), reproducibility (in terms of relative standard deviation: Pb 11-18%, Cu 6-10%) and the limit of detection (4 mu g/L for Pb and 7 mu g/L for Cu). The lowest detectable change (LDC), which is an important performance characteristic for this application, was estimated to be 4-5 mu g/L for Pb and 6-7 mu g/L for Cu. The life span of an SPE averaged 39 measurements per day, which is considered sufficient for intended monitoring campaigns. This work demonstrated the suitability of the integrated system for on-site detection of Pb and Cu emissions from large and medium urban areas discharging into small water bodies.

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