Postal Surveys and Self-Completion Questionnaires
Postal surveys (sometimes called mail-out surveys) usually involve mailing self-completion questionnaires to a targeted group of people, e.g. a client’s customers or people living in a certain area. Some database companies can also supply detailed information on “who lives where”, which can be purchased for market research and therefore make postal survey sampling more precise.
An important point to note when reading the discussion below is that the use of the traditional postal service for self-completion questionnaires is being overtaken to some extent degree by e-mail surveying.
Postal Surveys – The Advantages
The main advantages of postal surveys are that large numbers of questionnaires can be sent out, at relatively low cost. The questionnaires can include visual prompts, products for trial, and can be useful for asking the sorts of questions unlikely to be easily answered on the telephone (e.g. where a lot of quantitative detail is required).
Postal Surveys – The Disadvantages
A serious problem with postal surveys is that response rates are usually extremely low - generally lower than 20%, depending on such factors as the questionnaire’s length, presentation and subject matter, the incentives offered, ease of completion and respondents’ vested interest in participating.
Most importantly, the sample is not representative of the whole population, with some groups more motivated to return questionnaires than others. In postal customer surveys where we have been able to compare the samples gained from differing methods, we consistently find that it is the company’s most loyal and committed customers who return postal questionnaires, significantly biasing the results towards a favourable result.
The exception to this is staff surveys, sometimes called Organizational Climate Audits. In these cases, a postal methodology ensures respondent confidentiality, and much higher response rates can be achieved.