From the excellent Jonathan Haidt:
…I took the full text of the three most important New Atheist books—Richard Dawkins’ The God Delusion, Sam Harris’s The End of Faith, and Daniel Dennett’s Breaking the Spell and I ran the files through a widely used text analysis program that counts words that have been shown to indicate certainty, including “always,” “never,” “certainly,” “every,” and “undeniable.” To provide a close standard of comparison, I also analyzed three recent books by other scientists who write about religion but are not considered New Atheists: Jesse Bering’s The Belief Instinct, Ara Norenzayan’s Big Gods, and my own book The Righteous Mind. (More details about the analysis can be found here.)
To provide an additional standard of comparison, I also analyzed books by three right wing radio and television stars whose reasoning style is not generally regarded as scientific. I analyzed Glenn Beck’s Common Sense, Sean Hannity’s Deliver Us from Evil, and Anne Coulter’s Treason. (I chose the book for each author that had received the most comments on Amazon.) As you can see in the graph, the New Atheists win the “certainty” competition. Of the 75,000 words in The End of Faith, 2.24% of them connote or are associated with certainty. (I also analyzed The Moral Landscape—it came out at 2.34%.)
There is more here, and for the pointer I thank Eric Auld.