Long term survey strategy: summary report and framework to support decision-making

What does mixed mode mean?

The most common modes for collecting data in large-scale surveys are face-to-face, telephone, paper, and web. The first two are 'interviewer-administered' and the second two 'self-administered' or 'self-completion' modes. Typically, 'mixed mode' is used to describe surveys that combine two or more ways of collecting data from respondents, such that different respondents complete either the survey as a whole (or the same section of a survey) by two or more different modes. A survey that combines a primarily interviewer-administered survey with a web or paper self-completion element would more usually be described as 'multi-mode' rather than 'mixed mode'.

Mixed mode surveys can vary in terms of:

• mode of invitation (which may be different from the mode of completion)
• mode of participation or completion – there are 11 possible combinations of the four main modes (face-to-face, telephone, paper and web)
• sequencing – whether different modes are offered at the same time (concurrent designs) or in a particular order, so that a second mode is only offered if a participant has not responded by the first mode (sequential designs), or a combination of these.

Once all these possible variations are taken into account, the number of different possible mixed mode designs is very large. The review of surveys conducted for this research also highlighted the range of mixed mode designs being implemented in practice. Across the 21 surveys reviewed in detail, mode designs for their current or most recent wave included:

• Face-to-face (single mode) (e.g. Crime Survey for England and Wales (CSEW), English Housing Survey (EHS), Health Survey for England)
• Face-to-face, with telephone (and video) option for refusals (e.g. Childcare and Early Years survey)
• Face-to-face with telephone or face-to-face follow-up (e.g. Current Population Survey, USA)
• Push-to-web with paper option (e.g. Active Lives, British Election Survey 2019 Covid period, Food and You 2, Participation survey, GP Patient Survey)
• Push-to-web with telephone option (e.g. British Social Attitudes survey, Transformed Labour Force survey (TLFS))
• Push-to-web with paper and telephone follow-up of non-responders (e.g. Dutch Crime Victimization Survey, and a number of other Statistics Netherlands (CBS) surveys)
• Push-to-web with face-to-face or video call for non-responders (e.g. Next Steps Sweep 9)
• Web, face-to-face and telephone (e.g. Understanding Society)
• Telephone and web (e.g. National Survey for Wales).