Meaning
Metric in a privacy analysis that represents the probability that the privacy guarantee is breached. Analysts use the delta parameter to quantify the small chance that the privacy mechanisms fail to provide the intended level of protection. This value is typically set to be smaller than the reciprocal of the total number of individuals in the data set.
It acts as a safety margin for the epsilon guarantee.
Failure Probability
A non-zero value for the delta parameter allows for the use of the Gaussian mechanism, which often provides more utility than the Laplace mechanism in high dimensional spaces. This represents the likelihood that an algorithm might leak more information than the epsilon value suggests. Managing this risk is required for maintaining trust in large scale data releases.
Compliance Benchmark
Regulatory frameworks and commercial contracts often mandate specific thresholds for this value to guarantee a uniform level of protection. If the delta parameter is too high, the privacy guarantee becomes weak and may not satisfy legal requirements for data anonymization. Companies must balance this risk against the need for accurate data analysis.
Contractual Limit
Agreements between a data provider and a processor often specify a maximum allowable value for the delta parameter.