Relevance & Research Question: Since the early days of online market research there has been a debate about the comparability of online generated survey data versus data from “offline” sources. In the past there have been numerous studies on this matter, most of which were designed to prove the superiority of one or the other methodology.
What is usually not taken into account here is that different survey methodologies can have a complementary effect when used side by side. Telephone surveys for example struggle a lot in reaching young age groups and the so-called “Mobile Onlys”. Online surveys cannot reach elderly people who are not connected to the internet.
For the “INSA study 50plus” in 2011 – the year in which more than half of Germany’s population was aged 50 or over - a combined setup from both online and telephone generated sample was used.
Methods & Data: In August 2011 3,055 interviews were generated, out of which N=900 were surveyed per telephone and N=2,155 online. In order to guarantee a nationally representative sample, quotas were defined on age, gender and regions for both data collection methods. The INSA questionnaire contained 137 questions and covered 15 different topics. Since there was a significant increase of drop-outs expected for interview lengths of more than 20 minutes, both telephone and online questionnaires were split into three versions of identical length. Each respondent was randomly assigned to one of the three versions of the questionnaire. In the end, every question had been answered by a minimum of 1,000 respondents.
Results: At the closing date of this abstract the results of this comparative analysis had not yet been available. For GOR, both samples would be weighted, so that potential similarities and differences within the numerous topics can be analyzed in a sophisticated way.
Added Value: Because of the high amount of data that was generated, it will be possible to define a taxonomy which will explain in which of the topics of the Insa-Study the results will be biased by the method of data collection.