Including Don't know answer options in brand image surveys improves data quality

Sara Dolnicar

University of Queensland

Bettina Grün

Johannes Kepler University Linz


Survey research is one of the major sources of knowledge and market intelligence. Yet measurements used in survey research are not as standardised and well calibrated as measurement instruments in the sciences: true values cannot be derived as easily from a survey question as from a thermometer, for example. It is therefore crucial for any survey researcher to understand the effects various questionnaire design options have on the final results of a survey study.

There are many factors that can be varied in terms of questionnaire design: among others, the length of the questionnaire, formatting, colouring, the way the questions are asked and the answer options that are provided. An overview of key issues has recently been provided by Lietz (2010).