Recently, Internet auction companies provide their users with various options from which sellers and buyers can choose while trading at their web sites. This paper analyzes statistically the effects of the options on the results in Internet auctions. To do this, we develop a conceptual model of bidders' decision-making process based on previous research on bidders' behavior. In a conceptual model, we assume bidders take three steps to make their decisions. First, bidders decide whether to join an auction, they make decisions when they should enter to bidding war. Finally they choose their own bidding price. In this paper the statistical analyses use the data from two categories, "Computer" and "Fashion", at two Korean Internet Auction sites. We focus on the effects of four major options offered for sellers and bidders. Minimum increment bid levels, auction closing rules, proxy bidding and "buy-it-now" options have measurable effects on the results via bidding history in different ways. For sensitivity analysis on the effects of the options , we develop a simulation model programmed in SWARM.
