Usually, anything at 46 percent or above is a good indicator of real strength. Less than that, and you have to wonder about undecided voters.

■ It’s also worth looking at whether there’s a difference between registered and likely voters. In a presidential election year, I generally prefer looking at the registered voter numbers — with a caveat. That’s because many methods that screen for likely voters are poor and yield noisy data. Registered voter samples are larger, and there aren’t additional questions to add statistical noise. But here’s the caveat: Registered voter polls tend to overrepresent Democrats, so I often focus on the registered voter number and mentally shift it a point or two toward the Republicans.

■ This year, there’s also the question of whether to look at four-way or two-way polls. I’m not sold on which is best. This year’s third-party candidates don’t have the strong bases of a Ross Perot or John Anderson. It’s possible that the polls that name them will overestimate their support; it’s possible that the polls that do not name them will underestimate their support. For now, I’m inclined to split the difference.

Comparing Where They Were

To get a sense of whether a poll is good or bad news for a certain candidate, I usually compare the results of the poll with the polling averages or the last poll conducted by the same pollster.

■ If the poll is very different from the polling average, there’s a good chance it’s an outlier.

■ If the poll shows a big shift from a prior survey, I also wonder whether the previous poll was an outlier. If so, a candidate might appear to rebound simply because he or she was unusually weak in a prior poll. So compare that prior poll with the average of the time, too.

■ It’s also worth looking at whether the candidate has gained or lost vote share. When candidates fall without good reason, I often assume they’re likelier than not to win back their former supporters. I definitely take note when candidates have won more supporters than they’ve won before. If that happens a lot, it’s a real sign of strength.

■ I also look at the various measures of whether Mr. Trump has a ceiling: like a 50 percent “very unfavorable” rating, or 50 percent who say they would be scared of a Trump presidency. I’m not convinced that those measures actually represent a ceiling. But they very well might, and I am curious about whether he’s making progress by those measures.