Many posts on tactics for improving the exposure of a book seem to offer ideas, but little data to support how those activities help.
Teleread offers a little more insight, however, I find the survey results would need more definition.
What exactly are the results of? Is it a measure of effectiveness of the tactics, or simply a measure of what the respondents use? Who were the respondents? What is the effect these engagements tend to have on the sales or exposure of said book? Does it vary by genre?
I am looking forward to seeing more on the topic.