There are wide variations in Pennsylvania presidential polls. Experts explain why.
PITTSBURGH (KDKA) — With the presidency potentially dependent on how Pennsylvania votes in this year's presidential race, many political polls are being taken in the Keystone State.
But what explains the great difference in the poll results?
Harris-Trump polls in Pennsylvania
Five statewide polls out in the last day or so, and five different results in the neck-and-neck race between Vice President Kamala Harris and former President Donald Trump.
The Quinnipiac poll now has Harris ahead of Trump by six points, 51 to 45 percent.
The New York Times/Siena poll gives Harris a four-point edge, 50 to 46.
The Franklin and Marshall poll puts Harris ahead three points, 49 to 46.
The Washington Post poll gives Harris a one-point lead, 48 to 47.
The Marist College poll has Trump and Harris tied 49 to 49.
What explains the varying poll results?
Why might polls taken in Pennsylvania around the same time have different results?
"It may be the way the questions are posed. We do that very carefully," Tim Mally of the Quinnipiac poll said. "May be the time of day when they called. It may be any number of things."
Malloy said it matters how many people you sample. They polled over 1,300 people for their poll. Marist, which found the vote tied, called nearly 1,500. Both are solid numbers to call, but pollster Lee Miringoff sees other differences.
"You're talking about different organizations using different methodologies, different statistical formulas," Miringoff said.
Some pollsters allow email responses and automated calls, while others use human beings to ask questions.
"All of those choices, and there are many more we could talk about, all of those choices in the design of our surveys means they're doing something similar but not exactly the same," Berwood Yost of the Franklin and Marshall poll.
Margin of error
And then there's something called margin of error, which means polls aren't always what they seem, says Yost.
Franklin and Marshall's poll shows Harris ahead by three points but with a four-point margin of error, meaning you could subtract four from Harris and add four for Trump.
Given the margin of error in these polls, each of the pollsters with whom KDKA-TV spoke said there isn't much difference among any of these polls despite the six-point difference.
"Editorially, that's a big difference," Mirinigoff said. "Statistically, it is not."
Polls are just a snapshot in time, not a predictor of what happens on Nov. 5.
