I wanted to draw your attention to an outstanding series of articles by Lori Carrell, a professor of communication at the University of Wisconsin, who has done research in cooperation with the Center for Excellence in Congregational Leadership, which is owned and operated by Green Lake Conference Center/American Baptist Assembly in Wisconsin and has received funding from the Lilly Endowment. Each article is three pages long from Rev. magazine and contains some of the best practical advice about preaching you can find anywhere. Carrell has her Ph.D. in communication, is very familiar with how pastors think, is a Christian herself, and is a highly awarded professor. I am impressed. We need more of this kind of research on topics related to pastoring. 
Check out these PDFs online. (Links fixed Nov 8, 2019. BONUS DISCOVERY: All of Lori Carrell's articles on preaching are at the CECL (Center for Excellence in Congregational Leadership website!)
Lori Carrell, "Sermons Most Likely to Succeed: Do sermons actually change beliefs and behavior? An ongoing study reveals hard facts," Rev. Magazine (May/June 2007), 71-73.
Lori Carrell, "Sermons Most Likely to Succeed: Do sermons actually change beliefs and behavior? An ongoing study reveals hard facts," Rev. Magazine (May/June 2007), 71-73.
This is the most dense article–sharing findings from an extensive survey of what is most effective in preaching.
Lori Carrell, “The Perils of PowerPoint Preaching: Research reveals that the use of PowerPoint slides during preaching is often more of a distraction than a transformative tool,” Rev. Magazine (Mar/Apr 2008): 91-93.
Lori Carrell, “The Perils of PowerPoint Preaching: Research reveals that the use of PowerPoint slides during preaching is often more of a distraction than a transformative tool,” Rev. Magazine (Mar/Apr 2008): 91-93.
This article argues finds that much PowerPoint use is distracting.
Lori Carrell,"Are You Wasting Your Sermon Prep Time?" Rev. Magazine (May/June 2008), 91-93.
Lori Carrell,"Are You Wasting Your Sermon Prep Time?" Rev. Magazine (May/June 2008), 91-93.
This article explains what pastors do in sermon prep time and follows pastors who have tried to improve their effectiveness in preparation.
Lori Carrell,"Reaching the Choir: Are you transforming your listeners or simply telling them what they already know?," Rev. Magazine (July/August 2008), 95-97.
Lori Carrell,"Reaching the Choir: Are you transforming your listeners or simply telling them what they already know?," Rev. Magazine (July/August 2008), 95-97.
This article suggests a method for moving people from what they already know to specific challenges.
Lori Carrell,"Why Your Preaching Matters More Than You Think," Rev. Magazine (September/October 2008), 158-159.
Lori Carrell,"Why Your Preaching Matters More Than You Think," Rev. Magazine (September/October 2008), 158-159.
This article explains how greatly congregation members value preaching.
See also her book:
Lori Carrell, The Great American Sermon Survey (Mainstay Church Resources, 1999).
I give Rev. magazine credit for having regular columns from:
- David Kinnaman, author of UnChristian and president of The Barna Group;
- D. Michael Lindsay, assistant professor of sociology at Rice University, and a reputable sociologist.
Both move beyond the numbers to offer their take on what church leaders should do but they also both deal responsibly with statistics.