How can you predict a new book trend?

As the author of a new on how to spot trends, I have been visiting several bookstores, and I have had the chance to talk to booksellers. Then the question has come up, Okay. how can you spot a new book trend? Someone suggested that ) could also give an answer here. First of all: Trends do not just happen “out of the blue”. Trends are about human behavior, and to the extend that we can understand human behavior we can understand trends. Before there is a new subject or category that become popular in books there are some people – trendsetters – who have been buying “designer dogs” or using vodka with food (subjects that are books about this fall but that I have not been involved with in any way). In the past 3-4 years it has been possible to observe an interest in dogs that were charmingly different from traditional breeds and the use of premium vodka in connection with food among groups who are the most typical trendsetters according to the research that I have done: the young, designers, artists, gay men, celebrities, and wealthy people. So if you want to spot new book trends observe what these groups are doing, especially the ones that live in New York, Los Angeles, and San Francisco. Because there is a clear pattern: If something is interesting to the trendsetters now, a lot of people will be interested in the same thing in 3-5 years from now.

Henrik Vejlgaard, author, Anatomy of a Trend (McGraw-Hill, October 2007)