A postal survey is a quantitative data collection method in which paper questionnaires are sent by post to potential participants, the paper questionnaires are completed by the participants themselves (i.e. self-administered), and returned by post to the survey organisation.
Ipsos Point Of View
The decision to conduct a postal survey rather than a telephone, face-to-face or web survey should be guided by the available research budget and data quality requirements in terms of representativeness and measurement.
Postal surveys tend to be less costly than telephone surveys and are much cheaper than face-to-face surveys. Although they are more expensive than web surveys, postal surveys tend to have better population coverage because people without internet access are not excluded. However, both web and postal methods are not suitable for surveys among groups with poor literacy skills and language proficiency.
Response rates for postal surveys tend to be lower compared to face-to-face surveys but higher compared to telephone and web surveys. However, there are exceptions. For example, web surveys tend to achieve higher response rates than postal surveys in Iceland where internet penetration is almost universal. Response rates for postal surveys can be increased by using multiple and varied contact attempts, incentives, and a user-friendly questionnaire. We recommend using the Tailored Design Method (TDM) for postal survey implementation. TDM provides a set of efficient strategies for maximising postal survey response rates. (Dillman et al, 2014)
Postal surveys are a good choice for survey topics that are interesting or important for the study population, and where the questionnaire is relatively short and simple. However, postal surveys that use long questionnaires, complex routing, and cognitively difficult questions will produce lower quality data with more missing data (unit and item missing), routing errors and miscomprehension compared to the other data collection modes which benefit from computerisation and/or interviewer help and encouragement.