It is well known that some percentage of respondents participating in Stated Preference surveys will not give responses that reflect their true preferences. One reason is protest behaviour. If the distribution of protest responses is not independent of respondent or survey characteristics, then simply expelling protesters from surveys can lead to sample selection bias. Furthermore, WTP estimates will not be comparable across surveys. This paper seeks to explore potential causes of protest behaviour through a meta-study based on data from 40 different surveys. The objective of the study is to examine the effect of respondent specific variables as well as survey specific variables on protest behaviour. Our results suggest that some of the differences in WTP typically observed between different demographic groups, different elicitation formats and different question formats might actually be attributed to inherent differences in the propensity to protest. Our results indicate that the propensity for respondents to exhibit protest behaviour when asked a stated preference type valuation question depends on a number of specific factors, respondent specific as well as survey specific – knowledge which could potentially be used in order to reduce protest behaviour.