Quiz Entry - updated: 2026.07.14
What are the main benefits and limitations of differential privacy?
Benefits: provable, background-knowledge-proof protection with accurate group insights. Limitations: reduced precision, compute overhead, and a query/privacy budget that depletes.
| Benefits | Limitations |
|---|---|
| Mathematical guarantees (provable, not just promised) | Reduced precision for individuals/small subgroups |
| True privacy — neutralizes linkage attacks | Computational overhead to add/compensate noise |
| Accurate group insights preserved | Design trade-offs — more privacy = more noise, less granularity |
| Builds user trust (participate without fear) | Limited queries — running many on the same data erodes the guarantee |
The last limitation is the killer for interactive systems: every query spends the privacy budget, so DP suits well-defined, repetitive queries where the budget is managed, far less so open-ended exploration.
Tip: DP is great for "how many users did X?" asked a bounded number of times; it struggles with "let me poke at this dataset however I like."