In autumn of 2012 European Social Survey conducted a mixed-mode survey experiment under the supervision of Centre for Comparative Social Surveys, UK. Alongside UK, Sweden and Slovenia, Estonia was one of the participating countries. In this mixed-mode survey respondents were asked to answer the ESS questionnaire online and if there was no reaction to the postal invitation and the two reminders, the respondent was referred to the CAPI mode.
We aim to measure quality with respect to time variables and answer a number of questions. Was response time different in the two modes and has it affected data quality? Was there any random clicking in the web mode? Were response times different in the beginning and the end of the questionnaire? Did break-offs in the web mode have an effect on data quality?
Response times for every question in the CAWI mode and for question blocks in the CAPI mode were recorded. If response times in the web mode are very short then it might be that the respondent just chose some random answer. If random clicking is found, was this phenomenon more prevalent in the end of the questionnaire? Web mode allows break-offs and we assume that this helps to prevent random clicking, but it might have other unwanted effects.
We measure quality with number of missing values, differences in auxiliary variables available in the sample frame and significant differences in response distributions in the two modes that are not explainable by mode effects.