Mark Twain is credited with introducing into the American vernacular the phrase, "Lies, damned lies and statistics." One of the pervasive damned lies people take for granted is the results of political polls, especially in the Trump era. Most polls show him behind several of the myriad candidates vying to represent Democrats in the 2020 election. But the American Association for Public Opinion Research confirms that "national polls in 2016 tended to under-estimate Trump's support significantly more than Clinton's."
We are inundated with the latest polling on President Trump's approval rating and how people are likely to vote in the 2020 election. Both bode poorly for the president, but he doesn't believe them and neither should we. As an academic, I ran a research center that conducted local, state-wide and national public opinion polls and took a year's leave of absence from my university to work for Lou Harris, founder of the Harris Poll.
The reason why we shouldn't believe most of the current or future polling results about President Trump can be summarized in two words: Social Desirability.