Acknowledgments

For their detailed comments and suggestions, I would like to thank Andrew Karp, Guang Guo, Mike Patteta and David Schlotzhauer. For permission to use their data in the examples, I am indebted to Nicholas Christakis, Paula England, Sharon Harlan, Anne Keane, and Peter Tice. As usual, my editor, Judy Whatley, deserves a huge amount of credit for persistently but gently prodding me to finish this book.