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.

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    Clinton did win by 3 points, poll margin of errors are typically around three points, so the election polls were not incorrect. Election was decided by some very close states that polled close, or didn't have very much state-specific polling.
    – antlersoft
    Commented Feb 8, 2017 at 19:46
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    @Anoplexian Your quote seems rather selective. The claim of the article is that there is a margin of error of about 4 %points (8 %points for net approval rating / spread). I'll retract my vote, but I don't think that this is a good question for this site.
    – tim
    Commented Feb 8, 2017 at 20:20
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    @tim It is, but it shows that there is a possible bias, and Skeptics.SE is amazing at validating statistics. I'm not worried about the specifics, just whether or not a bias exists for these polls one way or another, which would not be a great question for Politics.SE.
    – Anoplexian
    Commented Feb 8, 2017 at 20:24
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    It's pretty well-known that all polls have issues of this kind. Are you asking if these issues apply to Trump Approval Rating polls, or are you asking if there is some extra factor at work here? Commented Feb 9, 2017 at 0:43
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    "unless there's a scandal or other notable event": Um, there's been one of those at least once a day since the inauguration. Commented Feb 9, 2017 at 3:22


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