Bias and Selective Sampling Continue to Skew polls in Biden’s Favor

A new poll showing Joe Biden beating President Trump by six points is under scrutiny for skewing the numbers in Biden’s favor using bad sampling. The poll, conducted by CNBC, oversampled younger voters by 20% and undersampled older voters by 15% and Republicans by 8% according to Top Trade Guru. It’s no surprise a sample size this divorced from the actual 2016 electorate would show Biden coming out ahead. Correcting for the skewed sampling, President Trump and Biden are in a statistical tie.

This overt bias in favor of the Democratic candidate is far from an anomaly. While the mainstream media insists they’ve corrected the wildly inaccurate polling methods of the 2016 election, there is little evidence to support this.

Market Research Foundation recently noted that the mainstream media is taking serious liberties with polling interpretation to spin a pro-Biden narrative. Last month, a slew of headlines trumpeted Biden’s double-digit lead as if it were new. What virtually no one mentioned is that last spring, long before the foreign coronavirus devastated entire sectors of the economy and cities from DC to Seattle descended into chaos, Biden led Trump by a 13-point margin. Polls have persistently favored Biden, and the fact that Trump hasn’t ceded more ground over the past year is surprising. Biden’s favorable numbers have actually fallen since last year, and his unfavorable numbers have risen, coinciding with an uptick in third-party and independent voters.

The major shift has not been toward Biden, but an increase in third party and undecided voters over the past year. Notice the share of third party and undecided voters rose from 5% in June 2019 to 9% in July 2020 in a recent Quinnipiac poll.

Biden versus Trump These numbers get more interesting when broken into demographic categories. Among men,10% are now undecided or would vote for someone else, among voters 18 to 34, 12% are now undecided or would vote for someone else, among African American voters, 14% are now undecided or would vote for someone else, and among Hispanics, a full 15% are undecided or would vote for someone else, as shown below.

Biden Trump undecided

Top Trade Guru also discovered sampling barely resembling the 2016 electorate in an August 10-11 Reuters/Ipsos poll. The pollsters constructed a sample of 50% Democrats and 37% Republicans, despite Republicans making up 48% of the 2016 electorate.

It’s not hard to paint Biden as a winning candidate when oversampling members of his own party and undersampling the opposition. This is one more example of mainstream polling bias intended to mislead instead of inform. In reality, President Trump is closing the gap with Biden by improving his standing with Independents, men, Black and Hispanic voters, and West Coasters. Trump gained 4 points with Independents, 3 points with men, and 2 points each with Black and Hispanic voters since late July.