Apparently Americans believe that a majority of Americans are either Muslim or Jewish

This is an absolutely mind-blowing survey of 1,000 Americans, with their responses weighted to make the survey group reflect a nationally representative population.

Respondents were asked to estimate what percentage of their fellow Americans fell into various groups. The answers were . . . what’s the word I’m looking for here?

Some more numbers, with the actual figure followed by the estimated figure:

Are Black: 12%/41%

Are Vegan or Vegetarian: 5%/30%

Are Hispanic: 17%/39%

Here’s one for Erik.

Are members of a union: 4%/36%

Even more amazingly, these figures tended to get even less accurate when the responses were from members of the minority groups themselves!

Black Americans estimate that, on average, Black people make up 52% of the U.S. adult population; non-Black Americans estimate the proportion is roughly 39%, closer to the real figure of 12%. First-generation immigrants we surveyed estimate that first-generation immigrants account for 40% of U.S. adults, while non-immigrants guess it is around 31%, closer to the actual figure of 14%.

An analogous, though much less extreme, reverse effect was observed with estimates of the size of majoritarian groups, with people tending to underestimate the size of those.

So for example people estimated that 66% of the population owns a car, when the true figure is 88% and that 65% of the population has a high school degree, when the correct figure is 89%.

What’s going on here? One thing for sure is that enormous numbers of Americans are just wildly ignorant of even the most basic statistical realities regarding their world, although a lot of these people can probably name several Ariana Grande songs. Part of this no doubt is that fear of minority groups of various kinds makes majoritarian group members exaggerate the size of the former, but this doesn’t account for the tendency of minority group members to make the same mistakes, often in an even more pronounced way. (Note that the mistakes become only slightly less egregious if one uses the median rather than the mean estimates people make).

Another factor is suggested by the pollsters:

One recent meta-study suggests that when people are asked to make an estimation they are uncertain about, such as the size of a population, they tend to rescale their perceptions in a rational manner. When a person’s lived experience suggests an extreme value — such as a small proportion of people who are Jewish or a large proportion of people who are Christian — they often assume, reasonably, that their experiences are biased. In response, they adjust their prior estimate of a group’s size accordingly by shifting it closer to what they perceive to be the mean group size (that is, 50%). This can facilitate misestimation in surveys, such as ours, which don’t require people to make tradeoffs by constraining the sum of group proportions within a certain category to 100%.

This reasoning process — referred to as uncertainty-based rescaling — leads people to systematically overestimate the size of small values and underestimate the size of large values. 

Well OK I guess . . . but how “rational” is it to rescale your perceptions to conclude that more than half of America is made up of Muslims and Jews? As Jonathan V. Last points out, wouldn’t you expect to see an extraordinarily different proportion of mosques and synagogues versus Christian churches, compared to the one that can be observed pretty much anywhere in America?

The re-election of Donald Trump to the presidency of the United States is truly a mystery that will never be solved.