Last years results were VERY interesting. HERE: http://beeinformed.org/2012/03/bee-informed-national-management-survey-2010-2011/
None of it is conclusive of course, it's not that kind of survey and study, and they're the first to admit it. But there are some takeaways that may challenge many of the popular beekeeping memes. (I hate that word) The one I noticed most was that much of the IPM programs don't seem to indicate any real gains for the costs and effort. Screened bottom board, relatively ineffective. Comb rotation - new combs seem to cost more bee lives; advice was given to only engage in moderate comb rotation. Mite treated hives survive more often. And the big surprise for me - providing a top entrance for over-wintering hives seems to have a noticeable survival effect. I think I'll make sure I have a spacer with a hole, on top, before tucking the girls away for winter.
If you haven't seen their explanation videos, go check them out on the BeeInformed YouTube Channel. I'm surprised how few views they have on these videos. I think understanding the data and their analysis is key to making good hive management decisions. Everyone should be reviewing what they're doing here!
Here's the videos I found most interesting.
General Explanation of the survey results (how to understand the context of their results):
http://youtu.be/Nrfe25qhU9Q
Varroa Control:
http://youtu.be/2s3wjMQfHo4
Brood Comb Management:
http://youtu.be/AbNYgbFOZek
Winter Preperations:
http://youtu.be/ixIRSxDLKGc