A Gallup poll shook the political world last week with a headline saying “G.O.P. Takes Unprecedented 10-Point Lead on Generic Ballot.” It reported that Republicans had their widest advantage to date on the question of which party voters would choose in the race for the Congressional seat in their districts.

Just a week later, the headline on the latest Gallup poll reads “Parties Tied at 46 Percent in Generic Ballot.”

Did the Democrats really make up so much ground in the last week?

Probably not. In fact, the result was just the latest cautionary tale about drawing too many conclusions from any single poll. And it is a reminder that every poll result carries a margin of sampling error. In Gallup’s case, it is plus or minus four percentage points.﻿