This graph shows how many people used different types of winter preparations and what their loss rates were. Now you may say "All of the methods helped." But rather than looking at the bar graph which is the average, look at the range denoted by the little black whiskers. That's the actual range of results. Statistical analysis dictates which difference is significant. But you can usually tell by which whiskers overlap.
For instance, the range of values for tar paper wrap overlap, demonstrating that the results were not significantly different while the use of an upper entrance were. In fact, the greatest differences were found among the Upper Entrance group.
The other three that were effective were the 'Equalize,' 'Lid Insulation,' and 'Mouse Guard.' The use of insulation or wrapping in tar paper are not shown to have different results than not using those methods.
I've never used equalizing, but I have Robin Hooded honey rarely. But I'm happy to say the ones that I have been recommending for years are effective, upper entrances and insulated lids. Mouse guards are pretty obvious, mice crawl in and eat honey and make nests. Upper entrances allow better ventilation and the release of humid air which can cause condensation. Insulated lids keep that condensation from collecting on the roof of the hive and dripping water on the cluster possibly killing it.
And as I've said for years, the bees don't heat the hive but rather heat the cluster. Insulation is largely irrelevant.