By Michael Stillman

Figuring out the value of a book is probably the most vexing issue facing booksellers and collectors alike. Not that there is any lack of data. Books have been auctioned in the open market for over three centuries. Knowledgeable booksellers have been placing prices on them for at least that long. There is an enormous wealth of information. The problem is that many of these valuations are old. How can we use this enormous body of pricing data when the ravages of inflation and changing taste have made them seemingly meaningless?

The answer is to convert these old prices into current values. We need a scale, something akin to what the Consumer Price Index does for a loaf of bread. Such a scale could translate the price a bookseller or auction placed on that book years ago into today's dollars. It would bring those old prices up to date. Now updated prices would not necessarily establish current value. Some books will have appreciated more than others in the intervening years. Nevertheless, it would tell you on average what that old price equals today. It will tell you the value that bookseller or auction placed on your book. In a world where accurate pricing information is very hard to find, this would be a major step.

At the AE, we have been compiling an enormous database (the AE Bibliographic Database) of priced records, primarily from auctions and top booksellers of many generations. Now approaching a million strong, and growing rapidly by the day, these records give us a unique window into book pricing over the past century. Now we have sorted and selected through these reams of data to generate a scale that reflects the yearly trends in book pricing. So far, the scale takes us back to 1914, but in time it will go even farther. Once the scale was created, it became possible to apply it back to each individual record to determine what that old price means in terms of today's dollars. "Book dollars," if you will, for this scale is based not on the price of bread but on the price of books. It is, so to speak, the Consumer Price Index of books.

As we noted, not all updated prices will reflect current values because of differing rates of appreciation. However, this brings us to a second, and maybe even more important use for these updated prices. The ability to convert old prices into current values will tell you how fast a book is appreciating relative to other books, which is just a polite way of saying whether it has been a good or a poor investment. Think about that. If a book sold for $100 fifty years ago, and sold for $200 yesterday, it's been a terrible investment. Most books have far more than doubled in fifty years. But, if that book sold for the equivalent of $100 in today's "book dollars" fifty years ago, and $200 today, that is a book which is appreciating at twice the normal rate. Converting old prices to current values enables you to see which books are good investments, which are not so good. Now, if your interest in books is strictly for the pleasure they bring you, then you need read no further. If at least part of your motivation in buying books revolves around money, then please continue.