The study looked at how changing the bidding system for public projects in Thailand from e-auction to e-bidding affects small and medium-sized contractor firms. They surveyed owners and managers of these firms and interviewed professionals to understand the differences. The results showed that factors related to finances were more important in e-auction, while situational factors were more important in e-bidding. Factors like "identity of competitors" and "general expense of the bidding process" became less important in e-bidding. The study also suggested that bid collusions may happen in e-auction, but switching to e-bidding could save public money in infrastructure projects.