A situation where a technical characterization having direct relevance has been replaced by one having contrived relevance, usually by way of analytical inference.
Surrogation is most commonly seen in the context of technical requirements where, in the legacy, they’re sometimes known as “in-lieu-of” requirements. In some cases, the surrogate can be construed as a Similarity Parameter.
Contrast with mere statistical reductions of data (e.g., Limit Condition).