Amazon.com has clarified its October 30 news release in an effort to eliminate ambiguity regarding the level of the sales increase for Search Inside titles since the program's launch on October 23. In the first five days, sales growth for titles included in Search Inside the Book outpaced growth for titles not in the program by nine percentage points. For example: If the books outside the program grew 1%, then the 120,000 titles in the Search Inside program grew 10%--not 1.09%. The sample of 120,000 searchable titles is counterbalanced by a control group consisting of the remaining titles that do not have Search Inside treatment. Amazon believes the nine percentage-point sales increase is a direct result of Search Inside the Book's integration with Amazon.com's 1-Click payment system, and Amazon.com's base of pre-registered, active customers. Search Inside the Book launched with 190 publishers, and Amazon has reported that 37 additional publishers have expressed an interest in participating.