This simulation model (in Python 3.8) is to describe and compare the outcomes in section 5 of the paper (The Influence of Anticipated Regretful Participants on Group Decisions). To check the frequency of behavioral divergence in groups of different compositions, we simulated the results from randomly generated GDM problems for the four types of decision-makers, and analyze how their choices change under the 4 different groups and differ from the perfectly rational group (control group).