not teaching,
still THINKING …
The margin of error is an important term that brings context to every poll and should be included in the reporting of every poll.
First, thank you to George Edmonson and Larry Dietrich, two fellow journalists. They both mentioned the all-important margin of error when they commented on our previous post about the difference between percent and percentage point in coverage of polls.
Now, a brief primer as explained in this piece by the Pew Research Center.
- Because surveys only talk to a sample of the population, we know that the result probably won’t exactly match the “true” result that we would get if we interviewed everyone in the population. The margin of sampling error describes how close we can reasonably expect a survey result to fall relative to the true population value. A margin of error of plus or minus 3 percentage points at the 95% confidence level means that if we fielded the same survey 100 times, we would expect the result to be within 3 percentage points of the true population value 95 of those times.
- The margin of error that pollsters customarily report describes the amount of variability we can expect around an individual candidate’s level of support.
- For example, … a hypothetical Poll A shows the Republican candidate with 48% support. A plus or minus 3 percentage point margin of error would mean that 48% Republican support is within the range of what we would expect if the true level of support in the full population lies somewhere 3 points in either direction – i.e., between 45% and 51%.
Keep in mind, too, the following details that also should be included in poll coverage to fully understand the results:
- Kind of poll
- Who conducted the poll
- Who paid for the poll
The Associated Press Stylebook offers an easy way for journalists to learn about and to brush up on the nuances of covering polls. And when journalists provide the many pertinent elements in their poll coverage, consumers also gain a better understanding of what it all means to them.
(These two profs are no longer teaching at Syracuse University’s Newhouse School, but we are still thinking.)