Interviewing individuals

The advantage of the personal contact methods is that they normally produce a high response rate, and this means that error, which might be introduced by many people refusing to co-operate in the survey, is minimized. The main disadvantage of the personal contact interview is that it is expensive. Survey costs are influenced by the complexity of information sought, the nature of the sample and the ease with which effective replies can be gathered.

To give some idea of the level of cost likely to be involved, in 2003 the cost per completed interview for a 20-minute structured questionnaire administered to consumers was £30-35. This includes all executive and administrative overheads. A survey of 750 consumer respondents commissioned from a research agency which is required to present a research design proposal, design the questionnaire, carry out the fieldwork, analyse the data and prepare a report, would result in a bill in the order of £26,000.

For industrial research, which requires more technically qualified and skilled interviewers and where respondents are more difficult to obtain, the cost could be very much higher per completed interview, although the generally smaller sample sizes used in such research may compensate for this. In international research the cost will vary. In the USA research costs are two to three times higher than in the UK, whereas in the developing world they are usually much cheaper. In carrying out an international survey coordinated from London, for example, the costs will be significantly higher than for a single-country survey.

Personal interviews may be carried out in a number of ways, as follows. Fully structured interviews

In fully structured interviews, the situation is 'structured' or controlled through the medium of the questionnaire. The interviewer must read out the questions and notes to respondents exactly as they appear on the questionnaire form, and may not add anything else, even by way of explanation to the respondent. This ensures that the responses, from many individuals, are given to precisely the same question, even though many interviewers may be involved in the data gathering process. In a fully structured interview, the respondent may only give one of the responses already listed on the questionnaire. This means that neither the interviewer nor the respondent may introduce material not previously originated by the researcher in designing the questionnaire.

Such questionnaires are used most commonly in 'head-counting' exercises, when the researcher wants to answer the question, 'How many people do this, or think that?' Fully structured questions are easy to ask and easy to answer. This makes it possible to use less technically qualified interviewers, since there is very little that they can do to bias the answers. Interviews can also be completed relatively quickly. Both of these factors will reduce fieldwork costs, which is why fully structured questions are used whenever possible.

Another practical advantage is that data processing and analysis of answers to this type of question are also relatively straightforward. Responses can be 'precoded' on the questionnaire, and all the interviewer has to do is to put a ring around the code number of the answer given. The completed questionnaire can go straight to the data-processing department where those numbers will be entered directly from the questionnaire for computer analysis. This can be done manually or through the use of scanners. The elimination of any intervening coding process between fieldwork and data processing is important in reducing both the time and costs of research. Computer-assisted personal interviews (CAPIs) using laptop or palmtop computers can save significant time in the processing of the questionnaires. Responses can be coded directly onto the computer and fed from anywhere in the world to the controlling office for central processing.

The main limitation of fully structured questionnaires is that they can only collect the data made possible by the content of the questionnaire. The respondent may only choose one of the answers given, not provide his own. If the questionnaire designer has erred, the final data collected will be erroneous. For example, a question may be presented in the form, 'Which of these six items is most important to you when considering the purchase of a camcorder?' and go on to list on a show card six possible factors which seem to the questionnaire designer to be the most important. The answers will make it possible to rank those six factors in order of their importance to respondents. However, if there is some other factor equally important as the six selected, it will not be discovered because respondents are given no opportunity to make this point. Many research designers attempt to resolve this problem by adding an 'Other response' category, but this too has limitations, as will be discussed in Chapter 8. In summary, then, there are practical advantages to using fully structured interviews, but the onus for the quality of data produced is most fully on the questionnaire designer, who is responsible for providing all possible answers as well as the questions.

Online Survey Champion

Online Survey Champion

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