Almost every day, I check the Presidential polls at RealClearPolitics, and then I shake my head. Ordinarily, there is some variation. This year, however, the differential is dramatic. Right now, for example, CNN/ORC has Clinton ahead by five points. Rasmussen Reports has Trump ahead by two. IBD/TIPP has it all tied up. The ABC News Tracking Poll has Hillary ahead by a whopping twelve, and the LA Times Tracking Poll (not listed by RealClearPolitics) has her ahead by one point.

There may be some method to this madness. I can think of two alternative explanations. The first is that the pollsters do not know what they are doing; the second is that some fancy footwork is going on.

It is easy to see why the pollsters might be baffled. When they do a poll, they ordinarily take a sample, and then they make adjustments after comparing their sample with the population (i.e., either the general population or the voting population). They want their sample to be representative of women and men; the various ethnic groups; Catholics, Protestants of various stripes, Jews, Muslims, Hindus, and the like; Republicans, Democrats, and Independents; and so forth and so on. So they weight the sample in light of these categories to make sure that it is representative. In ordinary circumstances, this is tolerably easy to do. When the world is in flux, a lot of guesswork is involved. This year there will be Republicans voting for Hillary Clinton and Democrats voting for Donald Trump. They all note this, and they try to adjust. Polling is not a science. It is an art. So the differential could be due to the fact that some of the pollsters are — in all honesty — making the wrong assumptions.