In thinking about eBay in my post on tricky ways to "Give Many" OLPC XO laptops, I was reminded about something that has bugged me for a very long time about eBay.
eBay’s data goldmine eBay is sitting on a vast goldmine of data that for the longest time I wasn’t sure they realize they have. eBay knows the market price of just about anything, from a soul (well, not anymore) to random and weird goods to a pretty specific hardware-configuration of a used laptop. Even more, they know the market price for these items over time.
And their data on these market prices is good, and well-accepted. It's standard practice in the nonprofits I've worked with to check the "fair market value" for donated technology by searching for something similar on eBay in order to provide a tax receipt to the donor. And naturally the price itself is the market price because, simply put, eBay is the market for these goods.
It looks like they do provide a set of this data (for a price) as part of the eBay Market Data Program:
The eBay Market Data Program offers rich consumer insight data about what is purchased on eBay and who is purchasing it. Access to this business intelligence can help you make effective buying and selling decisions for your business, regardless of whether you do business on eBay or outside of the eBay Marketplace.
Now, I'm not sure what the next step really is. I'd love to know if eBay would make a subset of this market data (scrubbing personal information out, naturally, but price, sale date, item description, and bidding history) available for free. I'm sure some stats folks would love it, as would market researchers and social scientists in general. I'm sure there are millions of interesting questions to ask and visualizations to create using such data, and there would still be a value-add for the paid version. They have a free non-commercial research API available through Data Unison, it seems, but I can't tell how much data is available through the system (it seems to only cover the past 30 days).