Practice makes the expert: The importance of training volunteers in the generation of phenological data from photographs of biodiversity observation platforms

(28%, z = 3.245, p < 0.001), while the untrained group had the highest incidence of classifying observations as Dk (60%, z = 8.094, p < 0.001) (Fig 3). The degree of agreement in the classification of observations varied by phenophase and rater group. For both species, the untrained groups had a very low rate of agreement in identi- fying new growth (L. nepetifolia: K = 0.253, z = 7.59, p < 0.001; N. glauca: K = -0.293, z = -7.99, p < 0.001). In contrast, for the reproductive phenophases (immature flower, mature flower Fig 3. Proportion of records classified as DK (Don’t know) (± CI 95%) for each rater group. According to multiple contrasts by Tukey tests, all rater groups are different. https://doi.org/10.1371/journal.pone.0282750.g003 PLOS ONE The training of volunteers as a promoter of phenological studies PLOS ONE | https://doi.org/10.1371/journal.pone.0282750 March 7, 2023 8 / 17