Candidate combination,P(collision),Secondary risk category,Why the risk is not fully captured by P(collision)
Member ID + Payer namespace alone,1e-6,Above threshold,"Does not meet the 2e-12 threshold and is excluded on that basis, independent of any administrative review."
Subscriber ID + Group Number + Payer namespace,~1e-8,Data independence risk; recyclability risk,"Group number is an employer-level field, not an individual-level field; it provides no incremental individual discrimination and may be shared by hundreds or thousands of members. Group number would transfer to a new member receiving a recycled subscriber ID and therefore provides no recyclability mitigation."