New York Times: “Conducting surveys in partisan primaries has long presented a challenge to pollsters, as it requires them to make assumptions about who will actually turn out to vote. Without mandatory party registration in Michigan, pollsters must guess who will show up on Election Day.”
“Many surveys assumed political independents would make up 30 to 40 percent of the electorate. These polls showed Dr. El-Sayed winning independents by a wide margin. While there is little authoritative detail available on the actual electorate, that assumption could have contributed to the challenge in polling the race, as voters who decline to identify with a political party tend to vote less frequently.”
