Treating wide agreement as evidence of truth.
A survey showing that four out of five dentists recommend a product is evidence about dentists' opinions; it does not by itself establish that the product is best. The fallacy is treating popularity as sufficient proof, not treating popularity as data.
In practice
- Nine of the ten agencies use the same forecasting model, which is offered as evidence the model is sound. All ten licensed it from the same vendor.
- A restaurant is chosen because the queue is longest, and the queue is longest because it was chosen.