How to Read the Ups and Downs of Polling in the G.O.P. Race

The polling roller coaster, as FiveThirtyEight’s Harry Enten put it, has begun. One week the headline is “Ted Cruz Surging in Polls.” Three weeks later, it’s “Marco Rubio Surges to Front of G.O.P. Pack.”

The wave of candidate announcements that began late last month has set off a new phase of volatile polling, when voters will rally behind news-making candidates and move on as soon as the next arrives.

Republican voters are just starting to tune in, and they start with few allegiances to this year’s deep field of candidates....