  In the 1980s, techniques to determine MVPs came to be called “population viability analysis” and the enthusiasm for the new framework was captured in the much-worn slogan: “MVP is the product, PVA the  process.”[23]  By the late 1980s, however, it became clear that the concept of a MVP was at best of very limited use. Leaving aside the conventional elements of the definition given above, even for the same species, populations in marginally different habitat patches often show highly variable demographic trends resulting in highly variable MVP estimates for them, with each estimate depending critically on the local  context.[24]  Moreover, as will be illustrated below for stochastic population models in general, the determination of MVPs suffers from irremediable structural uncertainty. This should not come as a surprise: what would have been more surprising is if legislative fiat had identified a scientifically valuable parameter. After the demise of the concept of the MVP, PVA began to be performed largely to estimate other parameters, especially the expected time to extinction of a population the estimation of which does not require any conventional choices—see the entry on   conservation biology.