Coverage is skewed towards local instances

[TobiasGoerke]

Coverage is calculated based upon the perturbation function.
The tabular perturbation function changes the non-fixed features randomly, given a predefined probability. As soon as this specified probability is < 1, non representative instances get generated, as the instance's value appear statistically more often.
This returns in a coverage that is not representative regarding the whole dataset.
If we, however, change the probability to 1 for generating coverage perturbations, we might violate anchor's theoretical description but make rules more intuitive.