mosaic effect [English]

Syndetic Relationships

InterPARES Definition

n. ~ The ability to piece together different datasets to reveal sensitive or confidential information that had been removed or obfuscated in the original datasets.

General Notes

The information in any given dataset, in isolation, may be limited and pose little risk to privacy or disclosure of confidential information. However, when combined with other datasets, especially publicly available datasets, it may be possible to cross-reference data elements to create a more complete picture that allows the reidentification (de-anonymization) of individuals and reveals confidential information about them.


  • OMB M-13-13 2013 (†685 p. 4): The mosaic effect occurs when the information in an individual dataset, in isolation, may not pose a risk of identifying an individual (or threatening some other important interest such as security), but when combined with other available information, could pose such risk. Before disclosing potential PII or other potentially sensitive information, agencies must consider other publicly available data – in any medium and from any source – to determine whether some combination of existing data and the data intended to be' publicly released could allow for the identification of an individual or pose another security concern. (†1565)
  • OMB M-13-13 2013 (†685 p. 9): As agencies consider whether or not information may be disclosed, they must also account for the "mosaic effect" of data aggregation. Agencies should note that the mosaic effect demands a risk-based analysis, often utilizing statistical methods whose parameters can change over time, depending on the nature of the information, the availability of other information, and the technology in place that could facilitate the process of identification. (†1568)
  • Tam and Clark 2015 (†686 p. 22): Every individual is a unique mosaic of publicly visible characteristics and private information. In a data rich world, distinct pieces of data that may not pose a privacy risk when released independently are likely to reveal personal information when they are combined – a situation referred to as the "mosaic effect". The use of Big Data greatly amplifies the mosaic effect because large rich data sets typically contain many visible characteristics, and so individually or in composition may enable spontaneous recognition of individuals and the consequential disclosure of their private information. (†1569)