Abstract
Explanations for the failure to predict Donald Trump’s win in the 2016 Presidential election sometimes include the “Shy Trump Supporter” hypothesis, according to which some Trump supporters succumb to social desirability bias and hide their vote preference from pollsters. I evaluate this hypothesis by comparing direct question and list experimental estimates of Trump support in a nationally representative survey of 5290 American adults fielded from September 2 to September 13, 2016. Of these, 32.5% report supporting Trump’s candidacy. A list experiment conducted on the same respondents yields an estimate 29.6%, suggesting that Trump’s poll numbers were not artificially deflated by social desirability bias as the list experiment estimate is actually lower than direct question estimate. I further investigate differences across measurement modes for relevant demographic and political subgroups and find no evidence in support of the “Shy Trump Supporter” hypothesis.
Appendix
Comparing Direct Question and List Experimental Estimates of Trump Support.
| Subgroup | N | Unadjusted estimates | Adjusted estimates | ||||
|---|---|---|---|---|---|---|---|
| Direct question | List experiment | Difference | Direct question | List experiment | Difference | ||
| Entire sample | 5290 | 32.5 (0.8) | 29.6 (3.4) | 3.0 (3.4) | 33.6 (0.7) | 33.0 (2.6) | 0.6 (2.6) |
| Strong democrat | 726 | 4.5 (0.8) | −4.3 (7.5) | 8.8 (7.6) | 5.0 (0.6) | 0.8 (2.4) | 4.2 (2.4) |
| Not very strong democrat | 1140 | 9.2 (1.2) | 5.0 (7.0) | 4.2 (6.9) | 8.0 (0.7) | 2.5 (3.2) | 5.5 (3.2) |
| Lean democrat | 409 | 13.0 (2.1) | 8.4 (11.0) | 4.6 (11.1) | 13.0 (1.4) | 7.6 (5.9) | 5.5 (6.1) |
| Independent | 1131 | 20.1 (1.5) | 24.3 (8.0) | −4.2 (8.1) | 18.8 (1.4) | 26.5 (6.9) | −7.7 (6.9) |
| Lean republican | 351 | 73.4 (2.7) | 55.9 (11.0) | 17.6 (11.1) | 59.8 (2.4) | 48.5 (12.5) | 11.3 (12.3) |
| Not very strong republican | 990 | 68.1 (1.9) | 72.1 (8.2) | −4.0 (8.0) | 72.4 (1.3) | 73.2 (6.9) | −0.8 (6.9) |
| Strong republican | 543 | 90.4 (1.3) | 80.5 (9.7) | 9.9 (9.7) | 84.1 (1.3) | 89.6 (6.5) | −5.5 (6.6) |
| Less than high school | 157 | 30.7 (4.2) | −4.3 (18.4) | 35.1 (18.4) | 33.6 (4.2) | 15.3 (9.1) | 18.3 (9.7) |
| High school or some college | 2793 | 34.4 (1.1) | 35.8 (4.7) | −1.4 (4.6) | 36.2 (1.0) | 36.7 (4.2) | −0.5 (4.2) |
| College | 1465 | 30.1 (1.4) | 27.4 (5.0) | 2.7 (5.0) | 32.5 (1.3) | 35.5 (4.7) | −3.0 (4.6) |
| Graduate school | 875 | 25.8 (1.7) | 10.9 (6.7) | 14.9 (6.5) | 27.1 (1.6) | 20.5 (4.7) | 6.6 (4.5) |
| Below 20th income percentile | 1038 | 30.7 (1.8) | 15.6 (8.2) | 15.1 (7.8) | 33.3 (1.2) | 31.0 (4.0) | 2.4 (3.9) |
| 20th–40th Income percentile | 1361 | 36.6 (1.7) | 38.4 (6.3) | −1.8 (6.2) | 35.6 (1.1) | 34.6 (2.8) | 0.9 (2.7) |
| 40th–60th Income percentile | 936 | 34.0 (2.1) | 19.7 (7.3) | 14.3 (7.3) | 34.0 (1.3) | 34.8 (3.3) | −0.8 (3.1) |
| 60th–80th Income percentile | 1151 | 33.9 (1.8) | 40.7 (7.4) | −6.8 (7.4) | 35.4 (1.4) | 39.7 (5.0) | −4.3 (4.9) |
| Above 80th income percentile | 804 | 27.2 (2.0) | 30.5 (8.8) | −3.4 (9.0) | 27.5 (1.4) | 21.4 (4.7) | 6.1 (4.7) |
| Men | 2332 | 36.9 (1.3) | 33.5 (5.3) | 3.5 (5.2) | 38.0 (1.1) | 33.5 (3.7) | 4.5 (3.7) |
| Women | 2958 | 28.4 (1.1) | 26.4 (4.4) | 2.0 (4.5) | 30.1 (1.0) | 32.7 (4.6) | −2.6 (4.6) |
| White | 3544 | 39.4 (1.1) | 38.0 (4.1) | 1.4 (4.1) | 39.9 (0.9) | 40.5 (3.3) | −0.6 (3.3) |
| Black | 446 | 10.3 (1.7) | 16.6 (10.9) | −6.3 (11.0) | 11.2 (1.7) | 22.0 (9.0) | −10.7 (9.0) |
| Hispanic | 804 | 24.4 (2.0) | 2.8 (9.7) | 21.6 (9.4) | 26.2 (1.9) | 9.0 (5.5) | 17.2 (5.4) |
| Other race | 496 | 20.3 (2.2) | 24.0 (11.6) | −3.8 (11.2) | 20.7 (2.2) | 28.5 (10.1) | −7.8 (10.0) |
| Unlikely voter | 1420 | 24.2 (1.4) | 20.7 (7.1) | 3.5 (7.1) | 24.3 (1.3) | 24.9 (5.9) | −0.5 (5.9) |
| Likely voter | 3870 | 36.5 (1.0) | 33.6 (3.7) | 2.9 (3.7) | 37.0 (0.9) | 36.0 (2.9) | 1.0 (2.8) |
All estimates incorporate sampling weights.
Bootstrapped standard errors are in parentheses.
Adjusted direction question estimates are predictions from a logistic regression.
Adjusted list experiment estimates are predictions from Imai’s (2011) NLS regression model.
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