Cooccur

Cooccur is a term used to describe the phenomenon of two or more events, items, or entities appearing together within a given context or dataset. It is used across disciplines to assess whether co-occurrence is random or indicative of underlying relationships, shared causes, or common environments.

In linguistics and corpus analysis, co-occurrence refers to words that appear near each other in text. Researchers measure the strength of these associations with metrics such as collocation strength and pointwise mutual information to identify meaningful word pairs or phrases that contribute to meaning or style.

In ecology, co-occurrence analyzes whether species appear together more or less often than expected by chance. This can reveal potential ecological interactions, such as competition or mutualism, or reflect shared habitat preferences. Methods include probabilistic models, permutation tests, and summary indices like the C-score to characterize patterns of distribution across communities.

In information retrieval and data mining, co-occurrence underpins the discovery of associations among items. Market basket analysis, for example, identifies items that frequently appear together, using measures like support, confidence, and lift to guide recommendations, inventory decisions, or targeted advertising. Co-occurrence data also informs network analyses and clustering in various domains.

Interpretation of co-occurrence requires caution, as observed patterns may arise from confounding factors, sampling design, or underlying structure rather than direct interaction. Different fields apply distinct models and assumptions, but the core idea remains the same: whether the joint appearance of elements exceeds, falls short of, or matches what would be expected by chance.