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July 6th, 2018 (Permalink)

Poll Watch: Is President Trump more popular than the FBI?

According to the following headline, he is:

Trump Approval Jumps As Attacks From Critics Backfire;
Trump Now More Popular Than FBI: IBD/TIPP Poll1

The July poll found that 41% approve of the job Trump is doing. That's the first time he's been above 40% since March 2017, and just 1 point below his highest approval rating of 42% during his first month in office.1

So, an alternative headline for this story would be:

Trump's Approval Rating Unchanged Since Taking Office

But you won't be seeing that anywhere but here.

Here's what supports the headline's comparison of Trump's approval rating with that of the FBI: "The poll found that just 39% have a favorable view of the FBI1." So, the difference between Trump's approval and that of the FBI is two percentage points. Most modern public opinion polls have a margin of error (MoE) of at least 3 percentage points, so this is not a significant difference. A more accurate appraisal of this result would be that Trump and the FBI are about equally unpopular. At the end of the article, where they always hide this information, you can read5:

Methodology: IBD/TIPP conducted the July poll from June 21 to June 29. It includes responses from 900 people nationwide, who were asked questions by live interviewers on phones. The poll's margin of error is +/-3.3 percentage points.1

This is actually a slightly small sample for a national public opinion poll, and the difference between the President's and the FBI's approval ratings is well within the margin of error2. There's another logical problem with the reporting of this poll, the first sentence of which reads:

Increasingly bitter and aggressive attacks on President Trump managed to bolster his approval rating, which climbed 5 points to reach the second highest level of his presidency, the latest IBD/TIPP Poll finds.1

This sentence claims that attacks on Trump served to "bolster"3 the approval rating, meaning that they supported it, which is a causal relation. However, the most that we know from this poll is that Trump's approval rating increased 5 points from the previous IBD/TIPP poll, and the attacks in question presumably happened either before or during the time that the poll was taken. Of course, it's possible that the attacks may have actually backfired, but it's also possible that Trump's approval rating would have increased even more if it hadn't been for those criticisms. Also, it's possible that the 5 point change was simply a random fluctuation. So, inferring causation in this case commits a causal fallacy4.

This is one of those polling reports in which, if you remove all the exaggeration, speculation, innumeracy, and illogicality, nothing much is left.

Notes:

  1. John Merline, "Trump Approval Jumps As Attacks From Critics Backfire; Trump Now More Popular Than FBI: IBD/TIPP Poll", Investor's Business Daily, 7/2/2018.
  2. See: How to Read a Poll: Margin of Error Errors.
  3. A bolster is either a long cylindrical pillow that is used to support the human body, or a structural part of a building that provides support. So, as a verb, to bolster means to support something.
  4. See: Causal Fallacy.
  5. I originally wrote here that the difference between Trump's approval rating and that of the FBI was only one percentage point, but it was two. The paragraph has been corrected.

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