 Great. They give us a good measure of attitudes. But interviewing a sample of Americans isn't as accurate as interviewing everyone in the country. That's why pollsters talk about the margin of error. The term describes the biggest likely difference between results when polling, say, a random sample of 1,000 and if we talked with every American. Here's the general idea. Say a survey finds 52% favor candidate red and the error margin is plus or minus 3 percentage points.