Citizen science: best practices to remove observer bias in trend analysis
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Citizen science, time series records over long periods of time, and wide geographic areas offer many opportunities for scientists to answer questions that would otherwise be impractical to investigate. Citizen scientists currently play active roles in a wide range of ecological projects; however, observer biases such as varying perception of events or objects being observed and quality of observations present challenges to successfully derive interannual variability and trend statistics from time series records. It is recommended that citizen science records, particularly those involving events such as plant phenology, should not be directly averaged across sites. The interannual variability expressed as an anomaly and trend expressed as a regression slope should be calculated for each site. Only the site level anomaly and regression slopes should be averaged to suppress observer biases.
KeywordsAnomaly Citizen science Observer bias Phenology Trend analysis
We would like to thank and commend the persistent work of John O’Keefe at Harvard Forest Experimental Forest for collecting and cataloging the unique field phenology data. We extend our thanks to the thoughtful and constructive comments of two anonymous reviewers.
- Krejcie RV, Morgan DW (1970) Determining sample size for research activities. Educ Psychol Meas 30:607–610Google Scholar
- Menzel A, Sparks TH, Estrella N, Koch E, Aasa A, Ahas R, Alm-Kübler K, Bissolli P, Braslavská O, Briede A, Chmielewski FM, Crepinsek Z, Curnel Y, Dahl Å, Defila C, Donnelly A, Filella Y, Jatczak K, Måge F, Mestre A, Nordli Ø, Peñuelas J, Pirinen P, Remišová V, Scheifinger H, Striz M, Susnik A, van Vliet AJH, Wielgolaski FE, Zach S, Zust A (2006) European phenological response to climate change matches the warming pattern. Glob Change Biol 12:1969–1976CrossRefGoogle Scholar
- Munson MA, Caruana R, Fink D, Hochachka WM, Iliff M, Rosenberg KV, Sheldon D, Sullivan BL, Wood C, Kelling S (2010) A method for measuring the relative information content of data from different monitoring protocols. Methods Ecol Evol 1:263–273Google Scholar
- Newton A (1896) A dictionary of birds. A&C Black, LondonGoogle Scholar
- O’Keefe J (2000) Phenology of woody species at Harvard Forest since 1990. Harvard Forest Data Archive: HF003Google Scholar
- Schmeller DS, Henry P-Y, Julliard R, Gruber B, Clobert J, Dziock F, Lengyel S, Nowicki P, Déri E, Burdrus E, Kull T, Tali K, Bauch B, Settele J, Van Swaay C, Kobler A, Babij V, Papastergiadou E, Henle K (2009) Advantages of volunteer-based biodiversity monitoring in Europe. Conserv Biol 23:307–316CrossRefGoogle Scholar
- Tweddle JC, Robinson LD, Pocock MJO, Roy HE (2012) Guide to citizen science: developing, implementing and evaluating citizen science to study biodiversity and the environment in the UK. Natural History Museum and NERC Centre for Ecology & Hydrology for UK-EOF. Available online: www.ukeof.org.uk.