Information about fish swimming down a river: each station represents an autonomous monitor that records if a tagged fish was seen at that location. Fish travel in one direction (migrating downstream). Information about misses is just as important as hits, but is not directly recorded in this form of the data.
A dataset with variables:
Was the fish seen? (1 if yes, and true for all rows)
Dataset provided by Myfanwy Johnston; more details at https://fishsciences.github.io/post/visualizing-fish-encounter-histories/