Interweave Press of Loveland, Colo., is the type of publisher that the Book Industry Study Group believes is not represented in traditional measurements of the size of the publishing industry. The publisher is part of a larger company, and the majority of its sales are generated by channels outside of bookstores. These are the kinds of publishers that, according to BISG's new report, "Under the Radar," generate billions of dollars of sales that are not included in statistics compiled by the Association of American Publishers or even BISG's own Trends study.

According to "Under the Radar" findings, about 63,000 publishers with sales of less than $50 million generate annual revenue of about $14.2 billion, and the majority of that revenue—about $11.5 billion—come from publishers with sales between $1 million and $49.9 million. Jeff Abraham, executive director of BISG, said that while some of that revenue is represented in current industry sales estimates—which puts total revenue at between $23.7 billion and $28.5 billion—a significant portion is not. "We've always heard anecdotal stories about how much activity occurs outside of traditional book publishing and bookselling. This study tries to quantify how much," Abraham said.

The study, conducted by InfoTrends, found that about 34% of the sales of publishers in the study come from bookstores and book wholesalers (including only 3.3% from the chains), although book wholesalers were found to be the fastest growing channel. Nonbook wholesalers, which service accounts such as health stores and sporting goods stores, represent about 20% of sales, while sales through catalogues contribute about 10% of revenue. In addition to wholesalers, the fastest growing segments were online retailers and direct-to-consumer.

Abraham knows that the "Under the Radar" findings challenge many industry assumptions, so he plans to put together an industry taskforce that will work on a process that can combine the results of the report with traditional industry measurements. He sees the study "as a good first step" in better understanding the size of the book market.