This thesis examines how bidder behavior in open bid English auctions in the real estate market may explain why sales prices often differ from the objects’ appraisal value. Using housing auction data in Oslo, Norway from 2014-2015 to parametrize the model, I show how the bidder’s evaluations that are time inconsistent, e.g., due to emotional factors, lead to such outcomes. Specifically, I develop a model, estimate certain parameters from the data, and define arbitrary distributions for others. To evaluate the results, I compare the outcome with a neo-classical simulation, where every bidder follows the same strategy of bidding marginally above the other’s bids while constraints hold. Outliers in the selling price to asking price ratio are generated in both directions with the behavioral model, which fit the range of the dataset more.