PIX

pIX, short for Privacy Information Exchange, is a hypothetical metric used in privacy-preserving data sharing and secure information exchange to quantify how well privacy is preserved in a mechanism while enabling useful data use. The concept envisions a single scalar index that can be used to compare different protocols, configurations, or pipelines on their privacy performance.

The pIX value is typically defined on a scale from 0 to 1, where 1 indicates maximal privacy protection and 0 indicates little or no privacy protection. It is not a formal standard, but a conceptual tool intended for discussion and benchmarking in research, product design, and policy contexts.

Calculation of pIX relies on a weighted combination of components, including data minimization (how little data is collected), anonymization strength (effectiveness of de-identification), resistance to re-identification (linkability and inferential risk), and the amount of controlled noise or perturbation applied (for example, differential privacy). A simple model uses pIX = w1*Dmin + w2*A + w3*R + w4*Noise, with weights summing to 1. The specific weights reflect domain priorities and the assumed threat model.

Applications of pIX appear in academic research, industry benchmarking, and regulatory discussions as a comparative lens for privacy-preserving techniques, such as data-sharing pipelines, analytics platforms, or synthetic data generators. It is intended to help stakeholders reason about trade-offs between data utility and privacy.

Limitations include dependence on the chosen adversary model, context, and assumptions; lack of standardization for weighting components; and potential oversimplification of complex privacy dynamics. See also differential privacy, de-identification, k-anonymity, and data minimization.