Preference models trained on homogeneous product sets may not generalize

Evidence

As impressive as this result is, there is a common factor that prevents the model from being generalized—all 13 of the loudspeakers were bookshelf models, a natural basis for a comparative product review in a magazine. All suffered from a lack of low bass, and many of them had common features: enclosure size, driver complement and configuration, etc. The population needed to be expanded to include larger products, using different driver configurations and types. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1213