<p><em>I don't think this is a duplicate of
<a href="https://psychology.stackexchange.com/questions/409/what-causes-systematic-under-or-over-estimation-of-general-knowledge-quantities">What causes systematic under- or over-estimation of general knowledge quantities?</a>, as the accepted (and only) answer doesn't answer this question.</em></p>
<hr />
<p><a href="https://today.yougov.com/topics/politics/articles-reports/2022/03/15/americans-misestimate-small-subgroups-population" rel="nofollow noreferrer">YouGovAmerica</a>
published these results, rounded to the nearest whole percent, from January 2022 to the question, &quot;<em>If you had to guess …</em>&quot;:</p>
<div class="s-table-container">
<table class="s-table">
<thead>
<tr>
<th>True</th>
<th>Estimate</th>
<th>What percentage of American adults?</th>
</tr>
</thead>
<tbody>
<tr>
<td>0%</td>
<td>20%</td>
<td>Have a household income over \$1 million</td>
</tr>
<tr>
<td>1%</td>
<td>21%</td>
<td>Are transgender</td>
</tr>
<tr>
<td>1%</td>
<td>26%</td>
<td>Have a household income over \$500,000</td>
</tr>
<tr>
<td>1%</td>
<td>27%</td>
<td>Are Muslim</td>
</tr>
<tr>
<td>1%</td>
<td>27%</td>
<td>Are Native American</td>
</tr>
<tr>
<td>2%</td>
<td>30%</td>
<td>Are Jewish</td>
</tr>
<tr>
<td>3%</td>
<td>30%</td>
<td>Live in New York City</td>
</tr>
<tr>
<td>3%</td>
<td>30%</td>
<td>Are gay or lesbian</td>
</tr>
<tr>
<td>3%</td>
<td>33%</td>
<td>Are atheists</td>
</tr>
<tr>
<td>4%</td>
<td>29%</td>
<td>Are bisexual</td>
</tr>
<tr>
<td>4%</td>
<td>36%</td>
<td>Are members of a union</td>
</tr>
<tr>
<td>5%</td>
<td>30%</td>
<td>Are vegan or vegetarian</td>
</tr>
<tr>
<td>6%</td>
<td>29%</td>
<td>Are Asian</td>
</tr>
<tr>
<td>6%</td>
<td>40%</td>
<td>Are a military veteran</td>
</tr>
<tr>
<td>9%</td>
<td>30%</td>
<td>Live in Texas</td>
</tr>
<tr>
<td>11%</td>
<td>34%</td>
<td>Are left-handed</td>
</tr>
<tr>
<td>12%</td>
<td>32%</td>
<td>Live in California</td>
</tr>
<tr>
<td>12%</td>
<td>41%</td>
<td>Are Black</td>
</tr>
<tr>
<td>12%</td>
<td>37%</td>
<td>Have an advanced degree</td>
</tr>
<tr>
<td>14%</td>
<td>33%</td>
<td>Are first-generation immigrants</td>
</tr>
<tr>
<td>17%</td>
<td>39%</td>
<td>Are Hispanic</td>
</tr>
<tr>
<td>22%</td>
<td>41%</td>
<td>Are Catholic</td>
</tr>
<tr>
<td>32%</td>
<td>54%</td>
<td>Own a gun</td>
</tr>
<tr>
<td>33%</td>
<td>47%</td>
<td>Have at least a college degree</td>
</tr>
<tr>
<td>34%</td>
<td>38%</td>
<td>Have a household income over \$100,000</td>
</tr>
<tr>
<td>37%</td>
<td>45%</td>
<td>Have a passport</td>
</tr>
<tr>
<td>42%</td>
<td>51%</td>
<td>Are Democrats</td>
</tr>
<tr>
<td>42%</td>
<td>56%</td>
<td>Are obese</td>
</tr>
<tr>
<td>47%</td>
<td>50%</td>
<td>Are Republicans</td>
</tr>
<tr>
<td>51%</td>
<td>55%</td>
<td>Are married</td>
</tr>
<tr>
<td>57%</td>
<td>58%</td>
<td>Have at least one child</td>
</tr>
<tr>
<td>62%</td>
<td>61%</td>
<td>Voted in the 2020 election</td>
</tr>
<tr>
<td>62%</td>
<td>50%</td>
<td>Have a household income over \$50,000</td>
</tr>
<tr>
<td>64%</td>
<td>59%</td>
<td>Are white</td>
</tr>
<tr>
<td>65%</td>
<td>49%</td>
<td>Own a house</td>
</tr>
<tr>
<td>66%</td>
<td>59%</td>
<td>Are fully vaccinated against COVID-19</td>
</tr>
<tr>
<td>67%</td>
<td>62%</td>
<td>Have a pet</td>
</tr>
<tr>
<td>70%</td>
<td>58%</td>
<td>Are Christian</td>
</tr>
<tr>
<td>77%</td>
<td>50%</td>
<td>Have read a book in the past year</td>
</tr>
<tr>
<td>82%</td>
<td>62%</td>
<td>Have a household income over $25,000</td>
</tr>
<tr>
<td>83%</td>
<td>68%</td>
<td>Have a driver's license</td>
</tr>
<tr>
<td>85%</td>
<td>76%</td>
<td>Own a smartphone</td>
</tr>
<tr>
<td>88%</td>
<td>59%</td>
<td>Have flown on a plane</td>
</tr>
<tr>
<td>88%</td>
<td>66%</td>
<td>Own a car</td>
</tr>
<tr>
<td>89%</td>
<td>65%</td>
<td>Have at least a high school degree</td>
</tr>
</tbody>
</table>
</div>
<p>Without exception, the small true answers were over-estimated, and the larger true answers were under-estimated, as can be seen by the blue line (estimates) being much more centralized and vertical than the red line (true values) in their graph:</p>
<p><a href="https://i.sstatic.net/QNzst.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/QNzst.png" alt="Graph showing True and Estimate lines crossing near where they are equal." /></a></p>
<p><strong>What causes people to over-estimate small proportions and under-estimate large proportions?</strong></p>
<p>It can't simply be the result of bias created by the media, as this moderation happens even when the results are blatantly impossible: the estimates based on non-overlapping racial categories add up to 225%.</p>
<hr />
<p>Note that I'm not asking about anything related to the individual topics themselves, only about this observed moderating effect.</p>

CC BY-SA 4.0
2022-11-20T07:56:16.133Z
The 0% true percentage of millionaire US households can be quite easily misinterpreted to mean that YouGovAmerica is suggesting there are **no US millionaire households**. That is badly done in my mind, but hey-ho 
Chris Rogers
CC BY-SA 4.0
2022-11-20T14:07:09.570Z
@ChrisRogers says "*YouGovAmerica is suggesting there are no US millionaire households*".  No, you are inferring that. What It does say is "*rounded to the nearest percent*". So 0% simply means less than ½%. But either way, 20% is very much larger, and that's the important idea to get from this.
Ray Butterworth
CC BY-SA 4.0
2022-11-20T19:22:09.893Z
You inferred what I said. I inferred nothing. I was just pointing out how some could easily misinterpret the data if it is read in the wrong way. *"can be quite easily misinterpreted to mean..."*
Chris Rogers
CC BY-SA 4.0
2022-11-20T21:14:11.697Z
@ChrisRogers, given that the numbers *are* rounded to the nearest integer, how could say ".25%" be better presented?
Ray Butterworth
CC BY-SA 4.0
2022-11-21T17:43:40.590Z
What sort of answer are you looking for? Psychological biases tend to be *observations* of behavior - they're not necessarily *caused* by anything besides "how our brains work". Something like https://en.wikipedia.org/wiki/Heuristic_(psychology) might also be relevant.
Bryan Krause
CC BY-SA 4.0
2022-11-22T15:11:11.080Z
@BryanKrause. That link was very helpful, making it worthwhile that I asked the question. Thanks.
[Availability](https://en.wikipedia.org/wiki/Heuristic_(psychology)#Availability) seems like the closest match.
My rough guess about this question is that people have more distinct memories of rarer events and so tend to remember them more easily.
Similarly people tend to ignore commonplace events and so they aren't the first thing to come to mind.
Ray Butterworth
<cognitive-psychology>
What causes people to over-estimate small proportions and under-estimate large proportions?
Ray Butterworth
# What causes people to over-estimate small proportions and under-estimate large proportions?

(Asked by: username_0 on 2022-11-20)

*I don't think this is a duplicate of
[What causes systematic under- or over-estimation of general knowledge quantities?](https://psychology.stackexchange.com/questions/409/what-causes-systematic-under-or-over-estimation-of-general-knowledge-quantities), as the accepted (and only) answer doesn't answer this question.*

---

[YouGovAmerica](https://today.yougov.com/topics/politics/articles-reports/2022/03/15/americans-misestimate-small-subgroups-population)
published these results, rounded to the nearest whole percent, from January 2022 to the question, "*If you had to guess …*":

| True | Estimate | What percentage of American adults? |
| --- | --- | --- |
| 0% | 20% | Have a household income over \$1 million |
| 1% | 21% | Are transgender |
| 1% | 26% | Have a household income over \$500,000 |
| 1% | 27% | Are Muslim |
| 1% | 27% | Are Native American |
| 2% | 30% | Are Jewish |
| 3% | 30% | Live in New York City |
| 3% | 30% | Are gay or lesbian |
| 3% | 33% | Are atheists |
| 4% | 29% | Are bisexual |
| 4% | 36% | Are members of a union |
| 5% | 30% | Are vegan or vegetarian |
| 6% | 29% | Are Asian |
| 6% | 40% | Are a military veteran |
| 9% | 30% | Live in Texas |
| 11% | 34% | Are left-handed |
| 12% | 32% | Live in California |
| 12% | 41% | Are Black |
| 12% | 37% | Have an advanced degree |
| 14% | 33% | Are first-generation immigrants |
| 17% | 39% | Are Hispanic |
| 22% | 41% | Are Catholic |
| 32% | 54% | Own a gun |
| 33% | 47% | Have at least a college degree |
| 34% | 38% | Have a household income over \$100,000 |
| 37% | 45% | Have a passport |
| 42% | 51% | Are Democrats |
| 42% | 56% | Are obese |
| 47% | 50% | Are Republicans |
| 51% | 55% | Are married |
| 57% | 58% | Have at least one child |
| 62% | 61% | Voted in the 2020 election |
| 62% | 50% | Have a household income over \$50,000 |
| 64% | 59% | Are white |
| 65% | 49% | Own a house |
| 66% | 59% | Are fully vaccinated against COVID-19 |
| 67% | 62% | Have a pet |
| 70% | 58% | Are Christian |
| 77% | 50% | Have read a book in the past year |
| 82% | 62% | Have a household income over $25,000 |
| 83% | 68% | Have a driver's license |
| 85% | 76% | Own a smartphone |
| 88% | 59% | Have flown on a plane |
| 88% | 66% | Own a car |
| 89% | 65% | Have at least a high school degree |

Without exception, the small true answers were over-estimated, and the larger true answers were under-estimated, as can be seen by the blue line (estimates) being much more centralized and vertical than the red line (true values) in their graph:

[![Graph showing True and Estimate lines crossing near where they are equal.](https://i.sstatic.net/QNzst.png)](https://i.sstatic.net/QNzst.png)

**What causes people to over-estimate small proportions and under-estimate large proportions?**

It can't simply be the result of bias created by the media, as this moderation happens even when the results are blatantly impossible: the estimates based on non-overlapping racial categories add up to 225%.

---

Note that I'm not asking about anything related to the individual topics themselves, only about this observed moderating effect.

**Tags:** cognitive-psychology

> **Comments:**
> **username_1**: The 0% true percentage of millionaire US households can be quite easily misinterpreted to mean that YouGovAmerica is suggesting there are **no US millionaire households**. That is badly done in my mind, but hey-ho   
> **username_0**: @ChrisRogers says "*YouGovAmerica is suggesting there are no US millionaire households*".  No, you are inferring that. What It does say is "*rounded to the nearest percent*". So 0% simply means less than ½%. But either way, 20% is very much larger, and that's the important idea to get from this.  
> **username_1**: You inferred what I said. I inferred nothing. I was just pointing out how some could easily misinterpret the data if it is read in the wrong way. *"can be quite easily misinterpreted to mean..."*  
> **username_0**: @ChrisRogers, given that the numbers *are* rounded to the nearest integer, how could say ".25%" be better presented?  
> **username_2**: What sort of answer are you looking for? Psychological biases tend to be *observations* of behavior - they're not necessarily *caused* by anything besides "how our brains work". Something like https://en.wikipedia.org/wiki/Heuristic_(psychology) might also be relevant.  
> **username_0**: @BryanKrause. That link was very helpful, making it worthwhile that I asked the question. Thanks. [Availability](https://en.wikipedia.org/wiki/Heuristic_(psychology)#Availability) seems like the closest match. My rough guess about this question is that people have more distinct memories of rarer events and so tend to remember them more easily. Similarly people tend to ignore commonplace events and so they aren't the first thing to come to mind.  

---

## 0 answers

