From Wikipedia article on Five safes:
"The Five Safes proposes that data management decisions be considered as solving problems in five 'dimensions': projects, people, settings, data and outputs. These are most commonly expressed as questions, for example:
- Safe projects: Is this use of the data appropriate?
- Safe people: Can the researchers be trusted to use it in an appropriate manner?
- Safe settings: Does the access facility limit unauthorised use?
- Safe data: Is there a disclosure risk in the data itself?
- Safe outputs: Are the statistical results non-disclosive?
These dimensions are scales, not limits. That is, solutions can have a mix of more or fewer controls in each dimension, but the overall solution is 'safe' independent of the particular mix. For example, a public use file available for open download cannot control who uses it, where or for what purpose, and so all the control (protection) must be in the data itself. In contrast, a file which is only accessed through a secure environment with certified users can contain very sensitive information: the non-statistical controls allow the data to be 'unsafe'."