nonresponse

In order to discuss ways of increasing the response rate it is necessary to consider briefly why people do not return questionnaires. Some people have died or moved before the questionnaires are sent out, whilst others simply refuse to complete questionnaires. Apart from people who have moved house, died, etc., probably the main reason why questionnaires are not returned is due to forgetfulness and inertia. This problem can be minimized in a number of ways. In constructing the questionnaire care should be taken in writing and ordering the questions to make it as simple and easy to complete as possible. The covering letter should be written so that the purposes of the study are explained and assurances should be given concerning the confidentiality of the data. A few days after sending the questionnaires a reminder card should be distributed, and second and even third copies of the questionnaire may be sent to nonrespondents, depending on finances. A shortened version of the questionnaire, asking key questions only, may be sent, or this may be administered by telephone.

A number of techniques exist which attempt to calculate the extent to which nonrespondents might differ from respondents. Depending on the data source, that data which is known about nonrespondents can be coded (see CODING) for analysis and comparison with respondents. For example, a study of young people using addresses obtained from careers offices may be able to build up a picture of nonrespondents which includes data on gender, age, examination results, employment status, etc. Also, replies can be weighted on the basis that respondents who reply to the final reminder have more in common with those from whom no response has been obtained than with those who replied earlier. It may also be possible to estimate some characteristics of the total population by using alternative data sources (e.g. other questionnaire studies, CENSUS material, etc.) and then the data can be weighted accordingly.