Illusory Correlation
Etymology
From Latin illusio, "a mocking, a deception," plus correlation, "a mutual relation." Psychologists Loren and Jean Chapman coined the term in the 1960s, showing that clinicians saw signature patterns in tests that the data did not support. Vivid, rare pairings are especially prone to being over-linked in memory.
noun · /ih-LOO-suh-ree kor-uh-LAY-shun/
Perceiving a relationship between two things that are not actually related.
What it names
Why we "just know" full moons bring chaos or that a lucky shirt works — memorable coincidences masquerade as patterns.
Example
Illusory correlation keeps the myth alive that the ER fills up on full-moon nights, though records show no such spike.
Related idea
Apophenia is the broad drive to see patterns in noise; illusory correlation is that drive fixed on two specific variables.