Box 1.

Key characteristics of ‘big data’

Volume: The sheer quantity of data, taking into account the number of persons whose data is contained in given datasets and the level of detail about each individual. Variety: The substantial diversity of data forms about individuals (e.g. structured, unstructured, images, audio) as well as the diversity of sources for that data (e.g. scientific data, user-generated data, web data). Velocity: The great speed at which data can be transmitted and analysed.