Policy experts' propensity to change their opinion along Delphi rounds

A key to successful Delphi process is to have some panellists to change their opinion as a result of considering the views of their peers. Despite this, studying the changes in opinions has not been in the research focus outside methodological approaches in the field of forecasting. In addition to forecasting, Delphi technique is also used widely in the fields of public policy and strategic decision-making in companies. We assessed opinion shift between Delphi rounds that were set up to evaluate reforms of specific agriculture and forestry policy measures. Theoretical postulates and findings from previous studies concerning consensus and extreme responses were assessed in this real-world Delphi process. The feedback in the process included both numeric and argumentative information from the previous round outcomes. We found that change in opinion was stimulated by the majority's stand whilst providing extreme responses to the arguments that were fed back meant perseverance of opinions. Additionally, interest groups showed differing response behaviour concerning the evaluated agriculture policy measures. In particular, panellists, who represented interest groups, were more persistent in their opinions compared to panellists representing other groups of expertise (e.g. administration, non-governmental organisations or research). Unlike interest groups, other groups or fields of expertise, age, gender or education did not offer elucidation over opinion change. Our results show not only the connection between changing opinions and the feedback information, but also that panellists can be analysed based on their propensity to change their opinion. This feature can be beneficial not only for policy- and decision-making but also, for example, for conflict assessments and for cases where further understanding of the group dynamics is desired.