Definition: Pseudonymisation refers to a technique that involves replacing or removing any information that could lead to identification of research subjects’ identity whilst still being able to make them identifiable through the use of the combination of code number and identifiers. This process comprises the following steps: removal of all identifiers from the research dataset; attribution of a specific identifier (pseudonym) for each participant and using it to label each research record; and maintenance of a cipher that links the code number to the participant in a document physically separate from the dataset. Pseudonymisation is typically a minimum requirement from ethical committees when conducting research, especially on human participants or involving confidential information, in order to ensure upholding of data privacy.

Related terms: <a href='/glossary/anonymity/'>Anonymity</a>, Confidentiality, Data privacy, De-identification, <a href='/glossary/pseudonymisation/'>Pseudonymisation</a>, Research ethics

References: Mourby et al. (2018), & UKRI (

Drafted and Reviewed by: Catia M. Oliveira, Helena Hartmann, Sam Parsons, Charlotte R. Pennington, Birgit Schmidt

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