Furthermore, suppose also that those five people had all previously said they did not wish to register as having a definite opinion on their preference. Then it should hardly be surprising if one in five changed their opinion.
Hence, I am puzzled by an article in the Wall Street Journal by Gerald F. Seib, Unaligned votes tilt rightward en masse. It states:
A massive swing by independent voters propelled the Republican Party to a series of key victories....
In House races nationally, Republicans won the votes of independents—voters who said they aren't affiliated with any party—by a 55% to 40% margin, a compilation of exit polls from across the country showed.
In other words, independents' preference did an almost complete turnabout over the last four years: They favored Democrats by 18 points then, Republicans by 15 points Tuesday.