Qualifying and measuring transparency: A medical data system case study

Transparency is a data processing principle enforced by the GDPR but purposely left open to interpretation. As such, the means to adhere to it are left unspecified. Article 29 Working Party provides practical guidance on how to interpret transparency, however there are no defined requirements nor ways to verify the quality of the implementation of transparency in a service. We address this problem. We discuss and define applicable metrics for transparency, propose how a measurement can be conducted in an operative system, and suggest a practical way in which these metrics can be interpreted in order to increase confidence that transparency is realised in a system.