However, other non-sampling errors can occur in market research, and it is essential to keep your eye out for them in polls:. The margin of error is critical to look out for but not the be-all and end-all of research errors. It is essential to analyze the methodology and ensure that the number of errors are limited. Read more about political polling here: The Accuracy of Political Polling. What is a Margin of Error? However, other non-sampling errors can occur in market research, and it is essential to keep your eye out for them in polls: The way a question is asked can result in errors e.
While AAPOR is influential, it only issues recommendations, and not all polling firms or media outlets follow them. Pollsters may also have incentives to overstate the precision of their results. Charles Franklin, a political scientist who runs the prominent Marquette Law School Poll, has experienced that dynamic firsthand. Franklin began running the Marquette poll in , after more than two decades doing academic survey research. That quirk works something like this: Take an imaginary poll that suggests that Joe Biden is leading Donald Trump by 5 percentage points: Biden is favored by 50 percent of the sample, and Trump by 45 percent.
But the 5 percentage-point gap between the two has its own margin of error — and that margin will be much larger than 3 points. C ommunicating uncertainty, of course, is something that has long dogged not just pollsters, but scientists writ large. Many climate scientists, epidemiologists, and meteorologists are tasked with juggling uncertain variables in order to understand and, as best they can, predict how complex systems will behave given certain inputs.
Instead of clear-cut answers, those models yield ranges of outcomes, often rendered as probabilities. In the case of climate models and epidemiological models, those results, despite the uncertainty, can have serious political implications. The reading public has, for the most part, learned to accept probabilities, and the underlying uncertainties, when it comes to, say, the weather. Few people are surprised or upset when a 25 percent chance of rain ends up delivering showers. But on other fronts — particularly those freighted with political baggage — many people respond to uncertainty with confusion, disappointment, and even anger.
In a conversation the week after the election, Franklin said he was feeling vexed over how to communicate uncertainty. But, he said, margin of error is a more straightforward, transparent calculation than whatever metric would likely replace it.
And, Franklin said, an excess of precision can actually detract from the work of pollsters. The basic problem, she said, goes beyond any one metric — not least because many people approach polls with high degrees of motivated thinking.
The level of observed change from one poll to the next would need to be quite large in order for us to say with confidence that a change in the horse-race margin is due to more than sampling variability.
Even when we do see large swings in support from one poll to the next, one should exercise caution in accepting them at face value. From Jan. Some of these might be quite far from the truth. Yet often these outlier polls end up receiving a great deal of attention because they imply a big change in the state of the race and tell a dramatic story. A result that is inconsistent with other polling is not necessarily wrong, but real changes in the state of a campaign should show up in other surveys as well.
The amount of precision that can be expected for comparisons between two polls will depend on the details of the specific polls being compared. In practice, almost any two polls on their own will prove insufficient for reliably measuring a change in the horse race.
As a general rule, looking at trends and patterns that emerge from a number of different polls can provide more confidence than looking at only one or two. Generally, the reported margin of error for a poll applies to estimates that use the whole sample e.
But polls often report on subgroups, such as young people, white men or Hispanics. Because survey estimates on subgroups of the population have fewer cases, their margins of error are larger — in some cases much larger.
A simple random sample of 1, cases has a margin of error of plus or minus 3 percentage points for estimates of overall support for individual candidates.
This would mean a margin of error of plus or minus 8 percentage points for individual candidates and a margin of error of plus or minus 16 percentage points for the difference between two candidates.
Some polling organizations, including Pew Research Center, report margins of error for subgroups or make them available upon request. Many poll watchers know that the margin of error for a survey is driven primarily by the sample size. But there are other factors that also affect the variability of estimates. Twenty-seven percent in the Newsweek poll said it was mostly Gore's fault. More voters continue to think Gore would do a better job on key issues such as health care, Social Security, education and taxes, the Newsweek poll found.
But Bush still edges Gore on leadership qualities, though more registered voters see Gore as honest and ethical, and intelligent and well-informed, the survey found. Meanwhile, a batch of state polls showed Bush with a wide lead in Kentucky and Indiana, but in a virtual dead heat with Gore in the key swing state of Ohio. The remaining 10 percent in Indiana, 7 percent in Kentucky, and 8 percent in Ohio were split among candidates from other parties and respondents who were undecided.
Pollsters said Bush's 4 percent margin in Ohio was within the 4. While Indiana has been conceded to Bush by most political strategists, Ohio and Kentucky have been regarded as up for grabs in the decisive Electoral College tallies, with each candidates devoting considerable campaign time to both states.
Comment: 1. The margin of error in each of the two estimates is at least this much, so it appears the Sun-Times and Fox are aggressively rounding their margins of error down.
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