1 Items: Gender System Justification

Items confirmed as identical across all included waves (2016, 2018).

2 Study Overview

Sample sizes and descriptive statistics for Gender System Justification by year
year	N	N (valid facet)	Mean	SD
2016	1500	1500	5.44	1.37
2018	2759	2759	5.20	1.54

2.0.1 2016 Sample

2.0.2 Sample

N=1500

To conduct a exploratory and a confirmatory large surveys during the general election, we hired a professional survey firm (SSI, a US-based market research company that recruits participants from a panel of 7,139,027 American citizens; more information can be found at www.surveysampling.com (now https://www.dynata.com/) to recruit a nationally representative sample of 1,500 Americans (50.7% women) who completed study materials during the general election from August 16-September 9, 2016. (Information about sampling and exclusion criteria is included in the Supplement). The age distribution was as follows: 18-24 (12.9%), 25-34 (17.6%), 35-44 (17.5%), 45-54 (19.5%), 55-65 (15.6%) and older than 65 (16.9%). The ethnic breakdown was: White/European American (82.5%), Black/African American (7.7%), Latino (5.9%) and “Other” (4.0%). Concerning religion, 67.6% identified as Christian, 17.1% as religiously affiliated but not Christian, and 15.3% as Atheist/Agnostic. With respect to education 35.1% indicated “high school only or lower,” 31.4 % indicated “some college,” and 33.6% indicated having received a “Bachelor” or “Graduate” degree. 2424 participants were directed to the survey, 1885 of which finished the survey (attrition rate 22%).

We followed recommendations to minimize the problem of careless responding in online studies. Specifically, we employed 10 random attention questions and time controls to check for data quality. There were 385 participants who failed more than one attention check or finished the survey in under ~22 minutes and were therefore excluded from the sample. For the 1500 participants who successfully finished the survey, completion time was 67 minutes on average (MD: 51min).

2.0.3 2018 Sample

2.0.4 Sample

N=TBD

Sample description for the 2018 PPBS CINT Post-election study to be added.

3 Descriptives

Descriptive statistics for Gender System Justification by year
year	N	Mean	SD	Median	Min	Max	Skewness	Kurtosis
2016	1500	5.44	1.37	5.50	1	9	-0.20	0.16
2018	2759	5.20	1.54	5.12	1	9	-0.14	-0.05

4 Demographics

4.1 Sex

4.1.1 Pooled Model with Year Interaction

Gender System Justification ~ Sex * Year
	Gender System Justification
Predictors	Estimates	CI	p
(Intercept)	5.04	4.94 – 5.15	<.001
Sex [Male]	0.79	0.65 – 0.94	<.001
year [2018]	-0.09	-0.22 – 0.04	.169
Sex [Male] × year [2018]	-0.30	-0.48 – -0.12	.001
Observations	4259
R² / R² adjusted	.049 / .048

4.1.2 Raincloud by Year

4.2 Age

4.2.1 Pooled Model with Year Interaction

Gender System Justification ~ Age * Year
	Gender System Justification
Predictors	Estimates	CI	p
(Intercept)	5.30	5.09 – 5.50	<.001
Age25-34 years	-0.30	-0.57 – -0.03	.031
Age35-44 years	0.08	-0.20 – 0.35	.583
Age45-54 years	0.12	-0.15 – 0.38	.379
Age55-64 years	0.25	-0.03 – 0.53	.076
Age [65+]	0.68	0.40 – 0.95	<.001
Age [65+ years]	0.73	0.52 – 0.93	<.001
year [2018]	-0.60	-0.86 – -0.33	<.001
Age25-34 years:year2018	0.62	0.28 – 0.96	<.001
Age35-44 years:year2018	0.40	0.05 – 0.74	.024
Age45-54 years:year2018	0.50	0.16 – 0.84	.004
Age55-64 years:year2018	0.39	0.04 – 0.74	.030
Observations	4259
R² / R² adjusted	.034 / .032

4.2.2 Raincloud by Year

4.3 Income

4.3.1 Pooled Model with Year Interaction

Gender System Justification ~ Income * Year
	Gender System Justification
Predictors	Estimates	CI	p
(Intercept)	5.11	4.90 – 5.33	<.001
Income [$15,000-$24,999]	0.08	-0.22 – 0.39	.603
Income [$25,000-$34,999]	0.21	-0.09 – 0.52	.173
Income [$35,000-$49,999]	0.27	-0.02 – 0.56	.069
Income [$50,000-$74,999]	0.31	0.04 – 0.59	.026
Income [$75,000-$99,999]	0.48	0.18 – 0.78	.002
Income [$100,000-$149,999]	0.65	0.33 – 0.96	<.001
Income [$150,000 +]	0.89	0.53 – 1.26	<.001
year [2018]	-0.23	-0.50 – 0.04	.099
Income [$15,000-$24,999] × year [2018]	-0.00	-0.39 – 0.38	.988
Income [$25,000-$34,999] × year [2018]	0.01	-0.38 – 0.40	.959
Income [$35,000-$49,999] × year [2018]	0.17	-0.20 – 0.53	.365
Income [$50,000-$74,999] × year [2018]	0.15	-0.19 – 0.50	.380
Income [$75,000-$99,999] × year [2018]	-0.08	-0.46 – 0.29	.662
Income [$100,000-$149,999] × year [2018]	-0.36	-0.74 – 0.02	.066
Income [$150,000 +] × year [2018]	-0.39	-0.82 – 0.04	.078
Observations	4259
R² / R² adjusted	.023 / .020

4.4 Ethnicity

4.4.1 Pooled Model with Year Interaction

Gender System Justification ~ Ethnicity * Year
	Gender System Justification
Predictors	Estimates	CI	p
(Intercept)	5.52	5.44 – 5.61	<.001
Ethnicity [Black/African American]	-0.82	-1.09 – -0.54	<.001
Ethnicity [Latino]	-0.21	-0.53 – 0.10	.181
Ethnicity [Asian/Pacific Islander]	-0.24	-0.78 – 0.29	.372
Ethnicity [Native American]	-0.39	-1.18 – 0.40	.336
Ethnicity [Other]	-0.37	-1.05 – 0.30	.282
Ethnicity [White]	0.87	0.04 – 1.70	.041
Ethnicity [Hispanic/Latino]	0.45	-0.41 – 1.32	.306
Ethnicity [Middle Eastern]	0.40	-1.03 – 1.83	.584
year [2018]	-1.01	-1.83 – -0.18	.017
Ethnicity [Black/African American] × year [2018]	0.92	0.04 – 1.80	.040
Ethnicity [Asian/Pacific Islander] × year [2018]	0.86	-0.17 – 1.89	.100
Ethnicity [Native American] × year [2018]	1.76	0.39 – 3.14	.012
Observations	4259
R² / R² adjusted	.045 / .042

4.5 Area

4.5.1 Pooled Model with Year Interaction

Gender System Justification ~ Area * Year
	Gender System Justification
Predictors	Estimates	CI	p
(Intercept)	5.37	5.27 – 5.46	<.001
Area [Rural]	0.19	0.03 – 0.35	.016
Area [Suburban]	0.30	0.16 – 0.43	<.001
year [2018]	-0.42	-0.56 – -0.27	<.001
Area [Rural] × year [2018]	0.26	0.04 – 0.48	.022
Observations	4259
R² / R² adjusted	.015 / .014

5 Political Orientation

5.1 Fixed-Effects Regression: Ideology ~ Construct * Year

5.1.1 Regression Table

	Gender System Justification → Ideology (Pooled)			Gender System Justification → Ideology (2016)			Gender System Justification → Ideology (2018)
Predictors	Estimates	CI	p	Estimates	CI	p	Estimates	CI	p
(Intercept)	1.82	-3.02 – 6.67	.461	1.02	0.44 – 1.60	.001	0.44	-4.42 – 5.30	.860
facet	0.52	-0.26 – 1.30	.194	0.75	0.67 – 0.84	<.001	9.37	8.74 – 10.01	<.001
year [2018]	-1.19	-6.30 – 3.93	.649
Age25-34 years	-0.85	-3.23 – 1.54	.487	0.06	-0.35 – 0.46	.774	-1.10	-4.84 – 2.64	.563
Age35-44 years	1.10	-1.35 – 3.54	.379	0.18	-0.24 – 0.59	.405	1.75	-2.08 – 5.58	.371
Age45-54 years	3.70	1.30 – 6.11	.003	0.46	0.05 – 0.86	.026	5.92	2.11 – 9.72	.002
Age55-64 years	4.27	1.81 – 6.73	.001	0.59	0.16 – 1.02	.007	6.40	2.58 – 10.22	.001
Age [65+]	2.82	-0.51 – 6.15	.097	1.31	0.89 – 1.73	<.001
Age [65+ years]	3.98	1.36 – 6.60	.003				5.12	1.42 – 8.81	.007
Inc	0.55	0.23 – 0.87	.001	0.01	-0.06 – 0.07	.831	0.82	0.35 – 1.30	.001
Edu	-1.18	-1.85 – -0.50	.001	-0.09	-0.21 – 0.03	.125	-1.70	-2.75 – -0.65	.001
facet × year [2018]	8.97	8.04 – 9.90	<.001
Observations	4259			1500			2759
R² / R² adjusted	.600 / .599			.238 / .234			.267 / .265

5.1.2 Scatter Plots by Year

5.1.3 Forest Plot: Meta-Analytic Pooling

5.2 Social Ideology

	Social Ideology (Pooled)			Social Ideology (2016)			Social Ideology (2018)
Predictors	Estimates	CI	p	Estimates	CI	p	Estimates	CI	p
(Intercept)	0.29	-4.40 – 4.98	.904	0.29	-0.23 – 0.81	.276	-4.39	-8.07 – -0.70	.020
facet	0.85	0.02 – 1.69	.046	0.85	0.76 – 0.95	<.001	10.29	9.61 – 10.97	<.001
year [2018]	-4.68	-10.23 – 0.88	.099
facet × year [2018]	9.43	8.43 – 10.43	<.001
Observations	4259			1500			2759
R² / R² adjusted	.545 / .544			.178 / .178			.242 / .242

5.3 Economic Ideology

	Economic Ideology (Pooled)			Economic Ideology (2016)			Economic Ideology (2018)
Predictors	Estimates	CI	p	Estimates	CI	p	Estimates	CI	p
(Intercept)	0.79	-3.65 – 5.24	.726	0.79	0.30 – 1.28	.001	1.54	-1.95 – 5.03	.387
facet	0.86	0.07 – 1.65	.033	0.86	0.77 – 0.95	<.001	10.09	9.45 – 10.74	<.001
year [2018]	0.74	-4.52 – 6.00	.781
facet × year [2018]	9.23	8.29 – 10.18	<.001
Observations	4259			1500			2759
R² / R² adjusted	.604 / .603			.200 / .200			.256 / .255

6 Party Identity Analyses

6.1 Party Identity (7-Point ANES) by Year

6.2 Party Identity Raincloud

6.3 Party Identity Regression with Year Interaction

	Party ID (Pooled)			Party ID (2016)			Party ID (2018)
Predictors	Estimates	CI	p	Estimates	CI	p	Estimates	CI	p
(Intercept)	0.67	0.58 – 0.77	<.001	0.67	0.58 – 0.77	<.001	0.63	0.57 – 0.68	<.001
facet	0.15	0.14 – 0.17	<.001	0.15	0.14 – 0.17	<.001	0.16	0.14 – 0.17	<.001
year [2018]	-0.05	-0.16 – 0.06	.403
facet × year [2018]	0.00	-0.02 – 0.02	.762
Observations	4259			1500			2759
R² / R² adjusted	.215 / .214			.173 / .173			.233 / .232

6.4 Forest Plot: Party ID Regression

7 Correlation Comparison

7.1 Cleveland Dot Plot: Correlations by Year

7.2 Forest Plots: Key Correlations

7.2.1 General System Justification

7.2.2 Economic System Justification

7.2.3 Ideological Self-placement [Left-Right]

7.2.4 Ideological Self-placement [Economic]

7.2.5 Party ID [G.O.P.]

7.3 Correlation Table by Year

Spearman correlations with Gender System Justification by year
label	2016	2018
Age	0.190	0.135
Anti-Pluralism [Populist Attitudes]	0.132	0.113
Blind Patriotism	-0.317	0.493
Competitive Worldview	0.018	0.116
Dangerous Worldview	0.091	0.164
Economic System Justification	0.575	0.588
Education	0.049	-0.073
General System Justification	0.521	0.647
Ideological Self-placement [Economic]	0.452	0.505
Ideological Self-placement [Left-Right]	0.456	0.511
Ideological Self-placement [Social]	0.422	0.490
Income	0.173	0.079
Male	0.290	0.164
Party ID [G.O.P.]	0.422	0.502
Religiosity	0.205	0.248
Right Wing Authoritarianism	0.385	0.489
Rural Area	0.068	0.106
Social Dominance Orientation	0.382	0.426
Support for Black Lives Matter	-0.420	-0.443
Support for Blue Lives Matter	0.227	0.247
Support for Civil Rights	-0.271	-0.272
Support for Environmentalism	-0.291	-0.376
Support for Feminism	-0.372	-0.448
Support for LGBTQ+	-0.397	-0.425