The correspondence between a largely behavioral
model and the portion of reality it claims to represent. One can think of such models as having equations whose
parameters must be chosen in order for the model to be specified. A parameter can either be assumed to have a certain value and is then hypothesized or it can be estimated (
see estimation ) from given
data and is then said to be identified. A model may be under-identified when not all of its parameters are identified or it may be over-identified when there are two or more inconsistent estimates of a parameter. (
Krippendorff )
