Anonymisation is a tool or process that allows data to be shared, whilst preserving privacy. The process of anonymising data requires that identifiers are changed in some way such as being removed, substituted, distorted, generalised or aggregated.

A person’s identity can be disclosed from:

• Direct identifiers such as names, NHS number, NI number and specific address information

• Indirect identifiers which, when linked with other available information, could identify someone, for example information on workplace, occupation or salary