The Statistical parity difference metric calculates the difference in the ratio of favorable outcomes between monitored groups and reference groups.

Do the math

The following formula is used for calculating statistical parity difference:

                                  (num_positives(privileged=False)      (num_instances(privileged=False) 
Statistical parity difference =   _______________________________ - _______________________________________

                                  (num_positives(privileged=True)       (num_instances(privileged=True)

The num_positives value represents the number of individuals in the group who received a positive outcome, and the num_instances value represents the total number of individuals in the group. The privileged=False label specifies unprivileged groups and the privileged=True label specifies privileged groups. In Watson OpenScale, the positive outcomes are designated as the favorable outcomes, and the negative outcomes are designated as the unfavorable outcomes. The privileged group is designated as the reference group, and the unprivileged group is designated as the monitored group.

The calculation produces a percentage that specifies the difference of the rate of favorable outccomes that are received by the monitored group in comparison to the reference group.

For more information, see Watson OpenScale Fairness Metrics and Transformers.

Parent topic: Fairness metrics overview