Use of secondary data

Primary data collection is challenging and with increasing electronic data capture in routine healthcare and other aspects of life, it is possible to address several epidemiological questions by robust analysis of such ‘secondary data’. There are considerable advantages in terms of scope, size, and speed of study to be balanced against the quality and depth of using primary data. Even when such direct contact is not required, there is often the need to extract necessary information from individual subject records such as medical files. There is often no alternative source of information, although the greater digitization of information is changing that scenario with the potential that the availability of such information might preclude the need for primary data.