Postal surveys, or "mail-out surveys," refer to the mailing of self-completion questionnaires to target groups. For example, the survey may be sent to a company's customers who live in a specific geographical area. The aim of the questionnaire is generally to gather information about customer opinions on certain topics. Questionnaires are straightforward, allowing respondents to choose answers from a predetermined range of responses. The questionnaire also generally provides the customer with the opportunity to make her own comments.
Quantifiable Results and Statistical Reliability
Postal surveys are one method that can be used to gather information from large, geographically diverse segments of society. The benefits of this method include coding, summarisation and analysis of results by numbers, sample statistics and percentages. The results can be expressed in quantified measures with a reasonable amount of statistical reliability. Because the results are quantifiable, this survey method helps to identify priorities for future services, measure current customer satisfaction and obtain customer views on current issues.
Postal survey questionnaires provide respondents with a certain amount of flexibility in terms of taking the survey whenever they feel up to it. There is no pressure, and respondents can take their time to reply whenever it is convenient for them to do so. This flexibility also enables respondents to consider their answers to complex questions and provide their best answers. Postal surveys offer the mailer flexibility in terms of being able to send promotional material and products to respondents together with the questionnaire. This serves as an incentive to respondents to send in their responses.
Low Response Rates
One of the major disadvantages of postal surveys is that the response rates are generally very low. Response rates depend on various factors, including the subject matter, length of the questionnaire, presentation of the questionnaire, difficulty level of the questions, respondent's vested interest in participating in the survey and the type of incentive offered. Response rates can be as low as 10 per cent or lower, and this leads to non-responsive bias in the collection of data.
Postal survey data is often not conclusive because it does not represent an entire section of the targeted population. Some groups appear to be more motivated to return the questionnaires, while others are not. A comparison of postal survey samples shows that for the most part, loyal customers are the ones who faithfully return their postal questionnaires. This tends to bias the results towards a favourable conclusion. Misinterpretation of the questions can happen without an interviewer present. This can lead to erroneous responses that skewer the results of the survey.