How cold is it? Warm enough to fly?
Unless you are going to treat the hive for varroa I wouldn't bother doing an ether roll at this time. Which may seem contradictory to what I wrote before. But, unless you are going to do something w/ the information, you may do more damage than the information gathering is worth, at this time of year.
Just to clarify - hive boxes and screened bottom boards often have different dimensions, and we try to level the playing field for discussion by stating mites per square inch and mention how many boxes of brood are over it. Frames with % brood would be better, or maybe even square inches of brood. Another factor to consider is how sticky is the sticky board? Can mites crawl off your sticky board in the cold? That could conceal great numbers of mites present in your colony, leading to an unanticipated winter loss and misleading information about your bees and their mites. Something to consider when trying to determine VSH tendencies for a potential breeder queen....
Jim Lyon, Mark, and Daniel Y - nice posts!
WLC - Thank you for the link! As far as to whom to refer for info? I'd go with the read-everything-and-think about how it applies to YOUR bees and THEIR little world of hexagons, sisters, momma queen, flowers, temperature, weather, mischief-makers, etc. school of thought...
So I'm glad we have Randy Oliver (donate to his site, everyone!), the universities, the internet, Beesource, The Hive and the Honeybee, all the other books, Germany's and Russia's and England's and Canada's scientific bee publications, etc. I also am glad that we have the observation hive!