By Michael Stillman

This month, the Americana Exchange initiates coverage of what we call "Trends in Book Auction Prices." We now provide three graphs that look at auction prices and sell-through rates going back over four years. Depending on whether you are buyer or seller, you may like or dislike what you see. We cannot change reality. What we do believe is an informed buyer or seller is always smarter than one who lacks information. That is the premise of this website, and these charts of auction trends provide one more data point of knowledge to help you make wise decisions.

Here are the three graphs, top to bottom:

1). 12-month moving average of median auction prices. Updated monthly, this chart graphs the median prices over the past 12 months. It shows you whether auction prices are trending up or down.

2). Year-to-year change in 12-month moving average. This compares the current 12-month median price, as shown above, with the same price as of one year ago. If prices have gone up, the graph will be positive; if they have gone down, it will be negative.

3). 12-month sell-through moving average. This is a chart of sell-through rates at auction, a 12-month moving average updated monthly. Find out whether auction houses are selling a higher, or lower, percentage of the books they offer.

Why do we use 12-month averages instead of just the most recent month's results? The answer is that there are too few auctions in any one month to provide a reliable sample. The graph would be a cacophony of peaks and valleys. A 12-month average smoothes out the spikes, enabling us to see what the trends truly are.

For those unfamiliar with moving averages, it simply is a regular updating of a constant period of time, in this case, one year. For example, our most recent 12-month period ran from May 1, 2008 - April 30, 2009. Once May auction results are received, a new point will be added to the graphs covering sales from June 1, 2008 - May 31, 2009.

The "Trends in Book Auction Prices" charts are found as a link from AE's Auction Search Page. This is the page that enables you to search book lots at upcoming auctions, view a summary of results and the top ten prices at the most recent 20 auctions, and view a calendar of future auctions and results of recently completed ones. You can click the following link if you wish to go directly to the new page of "Trends in Book Auction Prices."