Relevance & Research Question:
According to ESOMAR, online survey is already the most popular quantitative market research technique in the world (regarding research spending and number of interviews). The results of studies conducted via the Internet are frequently extrapolated to general populations and/or compared to results obtained by other modes. And thus the questions appear: Whether and in what circumstances could such generalisations be accurate, given limited coverage and systematic nonresponse error in online samples? Is the sole correction of socio-demographic quota enough to ensure results validity? If not, what other sample characteristics shall be controlled? Do the comparisons of online and offline results always make sense? How big is the impact of sampling effect and technique effect?
Methods & Data:
To answer the above questions we conducted a set of online and offline studies in 2009 and 2010. We paid a special attention to keeping different modes of measurements equivalent, according to timing, wording and look of the questions etc. We considered various research phenomena and various features for correction. The final study, which we will focus on here, took place in May 2010, in Poland. We gathered 3006 questionnaires from personal interviews, 5485 from online on-site recruitment and 6399 from online AccessPanel were gathered. The comparisons comprised of raw data results as well as of data weighed in various ways.
Results:
Demographic data correction makes online results better estimate some offline results, for some populations. However, just including additionally non-demographic characteristics put the modes differences within the bounds of a random error. Not all straight comparisons of online and offline results make sense. A technique and interviewer effects are for a range of phenomena not removable. We are going to show all the above in details during our speech.
Added Value:
The presentation will provide the audience with valuable insights of what needs to be known and controlled in online research to ensure high quality and validity of the results and when offline results can be a real reference to online. The topic shall be of interest not only for market researchers but also for academics.