1. Intelligent Database Systems Lab 國立雲林科技大學 National Yunlin University of Science and Technology A support system for predicting eBay end prices Presenter : Shu-Ya Li Authors : Dennis van Heijst, Rob Potharst, Michiel van Wezel DSS 2008

2. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 2 Outline Motivation Objective Methodology Experiments and Results Conclusion Personal Comments

3. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 3 Motivation The market price of a product is generally non-stationary at eBay — it fluctuates over time. Sellers Buyers How to make the auction be easier? Many bargains How to check prices of items? Reasonable sales price? Item description?

4. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 4 Objectives Finding these bargains can be made easier by using a support system. We create a support system for predicting end prices on eBay. Sellers Buyers End price Many bargains Check prices of items Reasonable sales price Item description

5. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 5 2. CART Methodology Feedback rating Number of pictures Item description Feedback rating Number of pictures 1. Input Data x Number of pictures Feedback rating 3. LSBoost Prediction price

6. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 6 CART (Classification And Regression Trees) CART  A binary tree.  Each decision node has two child nodes, which may again be decision nodes or leaf nodes. Yes Feedback rating ≦ 100 Feedback rating ≦ 120Number of pictures ≦ 5 No YesNo Number of pictures ≦ 10 $900 $1,100 YesNo YesNo

7. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 7 Experiments

8. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 8 Conclusion The predictions are based on a boosting model, which uses closed auctions of some product to predict prices for current auctions of the same product. Sellers can use this system to  submit draft versions of eBay auction pages.  get an indication of a reasonable sales price.  get the hints on terms to include in their ad text. Buyers can use this system to  check prices of items they have interest in and to locate bargains.

9. Intelligent Database Systems Lab N.Y.U.S.T. I. M. 9 Personal Comments Advantage  … Drawback  … Application  Hedonic Price  Investment