I'm reading the news and came across a story regarding Donald Trump's approval ratings and I'm unclear on who the survey respondents were. I have no basis to see which groups of people were represented by the approval ratings polls, and it appears to me that the approval ratings polls across a number of distinct attempts vary wildly.
This leads me to believe that some of these polls have some sort of institutional or confirmation bias that skews their numbers. I'm seeing on RealClearPolitics anywhere from a -15 point spread to a +4, numbers which should be well outside the margin of error for these (which seem to be between 1-5 points). Unless the ratings are such a roller coaster (which unless there's a scandal or other notable event I shouldn't see right?), am I wrong in assuming they shouldn't fluctuate as much as they are, and leads me to the conclusion above.
Is there any bias in the approval ratings reports that would cause such wild variations between polls or can these changes be explained statistically?
Edit for notability: Can You Trust Trump’s Approval Rating Polls?
In the article:
In the meantime, with polls in the news again, I’d urge my journalistic colleagues to do a better job of reporting on uncertainty when they report on polling data. Not only do polls have a margin of sampling error — for instance, the margin of sampling error on CNN’s poll of 1,000 adults is plus or minus 3 percentage points — but they also have other types of errors, such as nonresponse bias. The people who respond to polls — often under 10 percent of the population contacted — may not be representative of the population as a whole, and that creates a lot of challenges.