Rumor spread is proportional to its importance and lack of information.
Allport and Postman's 1947 formula: R ≈ i × a. Neither factor alone suffices — an important matter that is well documented generates no rumour, and an unclear matter nobody cares about generates none either.
In practice
- An acquisition is announced with no detail about the site, and the canteen produces four confident and incompatible accounts by Thursday.
- A school changes uniform suppliers without saying why, and by half-term the parents' group has decided the head is leaving.