The real margin of error for polls
In my daily scanning of the news, looking for stories that are both educational as well as entertaining, I came across this particular post: “WATCH – This Viral Video Perfectly Illustrates Why Americans Don’t Trust the Lamestream Media”.
The title is typical click-bait, hinting at something truly revealing that nine times out of ten turns out to be immensely disappointing. This time, however, I found that the post revealed a lie about political polls, almost as an aside, that is simply never noted.
The video itself is entertaining. It shows one particularly bad performance by a MSNBC political reporter, where in only about five minutes he used NBC polls to make a string of predictions about the presidential election, every single one of which turned out to be spectacularly wrong. I’ve embedded the video below the fold for your enjoyment.
What the post however noted that I found revealing was something else:
After all, these were NBC polls that Kornacki cited time and time again. Polls that showed Hillary Clinton leading Donald Trump in places like North Carolina, Georgia, and Ohio. The polls were terribly off-base. In some cases, the NBC numbers showed Clinton with a double-digit lead in states that she went on to lose. In other words, the polls were not by any means scientific, fair, or truthful.
Does the phrase “margin of error” ring a bell? Typically, it is between three and four percent, in order to be deemed usable, anyway. But NBC’s margin of error in Pennsylvania was 11 percent. [emphasis mine]
In the past decade or so political polls have routinely included what they call their “margin of error,” which generally for most polls ranges, as noted above, about three to four percent. This number is, and has always been a lie, however, as shown by the highlighted text. The real margin of error is the difference between what the poll predicted and what the actual results were. And for all of these NBC polls, the margin of error was not 3 to 4 percent, but anywhere from 11 to 30 percent!
In other words, these polls were worthless. Worse, they suggest some intentional manipulation, as they all made their error in only one direction (against Trump and for Clinton), much like the tampered global temperature data that we see coming from NASA and NOAA. It could be that there is confirmation bias going on here, producing results these liberal news outlets wish, but I do not think so. NBC, and its sister station MSNBC, have repeatedly in the past five years committed some egregious journalist frauds, all of which designed to make conservatives and Republicans look bad and to promote the interests of the Democratic Party. The network has made no moves to correct the problems. Nor has it fired anyone.
I think it very reasonable to suspect intentional fraud here, specifically aimed at helping the Democrats.
More important, this story illustrates why we should all laugh uproariously the next time we see a mainstream media journalist note pompously that the poll he or she is citing has a margin of error of 3%. He or she either doesn’t know what they are talking about, or they know very well and think you are too stupid to notice.
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