Informed consent is an ethical requirement for most research and must be considered and implemented throughout the research lifecycle, from planning to publication to sharing.
Failure to properly address issues of consent may restrict the opportunities for initial use of data, the publishing of your results and the sharing of the data.
For surveys, where personal identifiers such as people's names are not collected or are easily removed from the data file, written consent is often not gathered. Instead, the information sheet given to participants or the survey introduction would state that consent for the data being used for specified purposes is implied from participating in the survey, with a clause stating that an individual's responses would not be used in any way that would allow his/her identification. The information sheet should also provide details about any plans for sharing the data.
This is the usual practice for most large-scale surveys such as those undertaken by government departments in the UK.
If a survey extends beyond asking questions, to include activities such as a nurse visit, taking samples, making physical measurements, etc. then written consent is recommended. If personal data, sensitive data or confidential data are gathered during a survey, the use of written consent forms is recommended to assure compliance with the Data Protection Act and with ethical requirements.
For guidance, see our example survey consent statement as well as an example information letter from the British Household Panel Survey. You can view consent for other surveys in the UK Data Service data documentation attached to catalogue records in Discover.
You might also wish to look at Understanding Society as an example of how consent is dealt with in large, complex quantitative studies. There is also a discussion of consent for linking Understanding Society with administrative data in the Special Cases section.