In recent years, there has been a shift from surveys where data is obtained in interviews conducted in person by interviewers working in the field towards correspondence methods of data collection. With those methods, the respondents usually choose to take part in a poll based on an information letter distributed along with the questionnaire or link to the relevant online application. There are multiple reasons for this shift in survey methodology, from financial (lower data collection cost) to organisational (faster completion) to methodological (avoiding potential bias caused by the interviewers). The relative simplicity of correspondence interviewing also plays a role. Is hiring interviewers for surveys worth it then? What value can interviewers bring?
The Institute for Evaluations and Social Analyses (INESAN) conducted a survey in April 2012 focused on determining the rate of interest of Czech citizens in the results of public polls. In total, 1,013 valid personal interviews were conducted by interviewers with respondents aged 18–64. The sample was designed to ensure that the results obtained were representative of the opinions and attitudes of adult Czech citizens. The answers indicate that the greatest percentage of respondents make the decision on whether or not to take part on the basis of the circumstances such as the amount of the respondent’s available time or current mood. The presence, personality and demeanour of the interviewer are important for three-quarters of the interviewees. Any incentives offered are also significant, as more than one half of the respondents (56 %) admit their influence on their decisions.
The results show a marked difference in the effect of incentives on various groups of the population; incentives stimulate seven out of ten people in the age group of up to 20 years old to participate, whereas among middle-aged people (40–59) the incentives stimulate every other respondent. Furthermore, an offer of incentives is attractive for two-fifths of higher-class citizens, whereas in the other population groups (i.e. the lower and middle class) any incentives attract more than three-fifths of the interviewees to take part in public polls. In addition, incentives vary in efficiency depending on the respondents’ experience with polls; 62 % of people who have never been asked to take part in a poll would be convinced to participate on the basis of an offered incentive. By contrast, when it comes to a population that took part in a poll in the past, incentives can influence less than one half of the interviewees.
Graph: Influence of selected factors on participation in public polls
The results of the INESAN survey indicate that the interviewers play an important role. While they obviously cannot influence a respondent’s momentary mood or time available, their ability to intrigue a respondent, win their trust and convince them to take part in a poll is of key importance. Among other findings, the results correspond with the fact that surveys based on the respondents’ individual choice (polls and online surveys) where an interviewer is absent and where the offer of an incentive is the only motivation achieve a lower rate of response than data collected by interviewers. Incentives may enhance the involvement in a survey but alone they achieve lower efficiency than when combined with interviews conducted by interviewers.
In terms of the potential selective deviation caused by the offer of incentives, the importance of interviewers in surveys is growing, as they are more capable of selecting adequate respondents and significantly eliminating the discrepancies between the structure of the reviewed sample and the target group.