How many Democrats?

A Fox News poll last week found that 51% of the respondents said that Donald Trump should be impeached and removed from office and another 4% said he should be impeached but not removed.  On Sunday, Donald Trump tweeted "The Fox Impeachment poll has turned out to be incorrect. This was announced on Friday. Despite this, the Corrupt New York Times used this poll in one of its stories, no mention...of the correction which they knew about full well!"

He cited a story in the New York Post with the title  “Fox News Pollster Braun Research Misrepresented Impeachment Poll: Analysis”  The problem, according to the Post, was that 48% of the Fox sample said they were Democrats, "but the actual breakdown of party affiliation is 31% Democrat, 29% Republican and 38% independent, according to Gallup."  If you weighted by the "actual" distribution of party affiliation, support for impeachment was only about 45%. 

So how many Democrats are there?  The figure the Post gives is from the question, "In politics, as of today, do you consider yourself a Republican, a Democrat or an independent?"  However, most survey organizations follow up on the initial question by asking people who don't choose Democrat or Republican whether they lean towards one of the parties, and when they report the opinions of Democrats or Republicans they include the "leaners".  That was what the Fox News poll did.  Their first round got 40% Democrats, 33% Republicans, 27% independents.  On the follow up, 8% of the total sample said they leaned to the Democrats, 7% to the Republicans.  

The 40/33/27 distribution in the first round of the Fox poll is still pretty different from the 31/29/38 in Gallup.  Unfortunately Fox didn't report the party question they used, but in the most recent Fox News survey in the Roper Center, it was "When you think about politics, do you think of yourself as a Democrat or a Republican?"  That is, it didn't offer "independent" as an option--people had to volunteer it.  It makes sense that the number of reported independents would be lower with that question.

So the NY Post "analysis" just reflected ignorance about how surveys measure party affiliation.   The ratio of Democrats to Republicans is somewhat different in the Fox and Gallup polls, but the difference is small enough to easily be the result of chance in a sample of the usual size.  Gallup's most recent estimate, based on averages of surveys in July-Sept 2019, is 47% Democrats and 42% Republicans (including "leaners"), not much different from the 48% and 40% in the Fox poll. Gallup reports that "the current Democratic advantage is among the larger ones for the party over the past two decades."

So 48% Democrats, and by implication, 51% support for impeaching and removing Trump from office sound about right.