The Great Donald Trump Polling Gap, Not Explained

Here's something pretty interesting: it turns out that Donald Trump does significantly better in robocall and online polls than he does in traditional live-interview polls. Harry Enten shows the difference on the right. As Trump might say, it's yuuuge: a full ten-point difference in the latest polling.

This is peculiar for several reasons. First, this gap didn't really open up until September. Second, we never saw a gap of this size in 2012. Third, since Enten doesn't mention this, I assume other 2016 candidates don't show gaps anywhere near this big.

So what's going on? Enten suggests a few reasons why non-live polls might be a bit less accurate, but in the end he doesn't really know. And whatever the reason, why does it affect only Trump in a substantial way? This is very mysterious. And until people start voting, we don't even know for sure which type of poll is more predictive. It's just another way in which this year's Republican primary is winning awards for all-time weirdness.