[Ed. – This article was published on Dec. 1, 2015 but seems pretty relevant this morning. Appropriately, it appeared at FiveThirtyEight, the website begun by Nate Sivler.]
Does Donald Trump lead the race for the Republican presidential nomination? Or does he lead it by a “yuuuuuge” margin? Bloomberg recently released a poll that gave Trump 24 percent to Ben Carson’s 20 percent. On the same day, Ipsos released a poll that put Trump at 37 percent to Carson’s 14 percent. Normally, I’d suggest you average the results and move on. But these two polls are emblematic of a deep divide this year first noted by Jonathan Robinson: The Bloomberg poll was conducted over the phone with live interviewers; the Ipsos poll was conducted online.
Trump has averaged 23.4 percent in live-interview polls since entering the race in mid-June. That’s 5.9 percentage points lower than his standing according to automated phone polls (29.3 percent) and 5.7 percentage points lower than his support in Internet polls (29.1 percent). Here’s the gap since Trump entered the race (to simplify things, I’ve combined automated phone and Internet polls)….