How good are citizen science data?
It really depends on the question being asked.
At eOceans, the question determines the data that can and cannot use, and the method used to select the appropriate data is pre-defined, defensible, and transparent (e.g., in a publication).
For example, if we are helping someone describe a species-specific question like “What is the seasonal distribution of leopard sharks, Stegostoma fasciatum?” then we may restrict the data to include observations only made by experts, such as people recording them accurately over a 2+ year time period. On the other hand, if we are helping a community understand the socioeconomic or cultural value of shark interactions, we may decide to use all observations where someone logged a shark regardless of their expertise and experience.