The following article by Ruy Teixeira, author of The Optimistic Leftist and other works of political analysis, is cross-posted from his Facebook page:

How Worried Should You Be About Trump’s Rising Approval Ratings?

On the one hand, if his approval rating is truly going up a lot, you should be very worried. No matter who the Democratic nominee is, they’ll have a hard time beating Trump if his approval rating starts pushing 50 percent..

Since Gallup just reported a reading of 49 percent, perhaps it’s time to panic? Not really. The Gallup number appears to be an outlier; the current 538 poll-averaged approval number is 43.9 percent, at the high range of Trump’s first term but far below 49 percent. Still, the 538 rolling average does show an increase of about 2 and a half points in Trump’s rating since August.

Interestingly, even that increase could owe more to survey sampling problems (“differential nonresponse bias”) than an actual rise in Trump’s popularity. Political scientist Jacob Long explains on the Post’s Monkey Cage blog:

“As occasional Monkey Cage contributor [statistician] Andrew Gelman has explained, differential nonresponse bias refers to situations in which changes in polling results are caused by shifts in who responds to the polls rather than actual changes in public opinion. It may be that Trump’s approval is going up because Democrats feel demoralized by the apparently hopeless impeachment trial and so don’t feel like talking to pollsters. Or it could be that Republicans feel so moved to support Trump at when he’s under attack that they are more likely to talk to pollsters than usual.

One example of this occurred during the 2012 election. Gelman and his collaborators Sharad Goel, Doug Rivers, and David Rothschild showed that after Barack Obama’s poor first debate performance against Mitt Romney, the polls showed Romney’s chances of beating Obama surging. But when looking at the survey responses from a group of people who had been asked about their voting intentions repeatedly throughout the campaign, Gelman and colleagues found that survey respondents’ minds weren’t changing after the debate. Rather, Obama supporters were less likely to respond to the surveys during that negative news cycle.

As Trump was heading toward a widely-expected acquittal in the impeachment trial, were Democrats similarly just feeling unenthused about talking to pollsters?…

With Gallup, it looks like almost all the variation in Trump’s job approval from one poll to the next can be explained just by looking at how many of each party’s supporters are in their sample…..Gallup’s shift is the clearest and most dramatic among the pollsters, but there remains a general pattern that is largely consistent with probability that results are partly determined by differential nonresponse….

This means there is reason to believe Trump’s historically stable job approval hasn’t changed much since before the impeachment process began.”

Of course, none of this proves that Trump’s “true” approval rating is not creeping upwards in the real world. It could be and Long responsibly outlines some of the reasons why such a trend cannot be ruled out. But his quantitative analysis does make differential nonresponse bias a very plausible explanation for the recent upward trend in Trump’s approval rating.

So don’t panic…at least not yet.