Small values in big data: The continuing need for appropriate metadata

Ecological Informatics
By: , and 

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Abstract

Compiling data from disparate sources to address pressing ecological issues is increasingly common. Many ecological datasets contain left-censored data – observations below an analytical detection limit. Studies from single and typically small datasets show that common approaches for handling censored data — e.g., deletion or substituting fixed values — result in systematic biases. However, no studies have explored the degree to which the documentation and presence of censored data influence outcomes from large, multi-sourced datasets. We describe left-censored data in a lake water quality database assembled from 74 sources and illustrate the challenges of dealing with small values in big data, including detection limits that are absent, range widely, and show trends over time. We show that substitutions of censored data can also bias analyses using ‘big data’ datasets, that censored data can be effectively handled with modern quantitative approaches, but that such approaches rely on accurate metadata that describe treatment of censored data from each source.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Small values in big data: The continuing need for appropriate metadata
Series title Ecological Informatics
DOI 10.1016/j.ecoinf.2018.03.002
Volume 45
Year Published 2018
Language English
Publisher Elsevier
Contributing office(s) Coop Res Unit Leetown
Description 5 p.
First page 26
Last page 30