  The paper presents a construction of a quantitative measure of variability
for parameter estimates in the data fitting problem under interval uncertainty.
It shows the degree of variability and ambiguity of the estimate, and the need
for its introduction is dictated by non-uniqueness of answers to the problems
with interval data. A substantiation of the new variability measure is given,
its application and motivations are discussed. Several examples and a series of
numerical tests are considered, showing the features of the new characteristic
and the specifics of its use.
