1. A population comparison method comprising: storing a list of population members and corresponding member characteristics parameters describing each listed member, wherein the population members are hydrocarbon reservoirs; receiving a description for a new population member, said description missing one or more member characteristics parameters, wherein said at least one missing member characteristics parameters is a key parameter (KP); automatically estimating a value for at least one missing member characteristic parameters responsive to stored said member characteristics parameters; supplementing said description with each estimated value; automatically comparing the supplemented description against stored descriptions for each listed member; selecting a subset of listed members as analogous members for said new population member responsive to the comparison; and extracting an uncertainty characterization of said selected subset automatically responsive to selection.