float
The estimated probability that a given individual sharing
these quasi-identifier values is in the dataset. This value,
typically called δ, is the ratio between the number of
records in the dataset with these quasi-identifier values,
and the total number of individuals (inside *and* outside
the dataset) with these quasi-identifier values. For
example, if there are 15 individuals in the dataset who
share the same quasi-identifier values, and an estimated 100
people in the entire population with these values, then δ is
0.15.