Global Psychotrauma Screen (GPS): psychometric properties in two Internet-based studies

Figures & data

Table 1. Sample demographics

	GC-TS Sample	MTurk Sample
	M (SD) or n (%)	M (SD) or n/%
Age	36.7 (13.6)	35.6 (12.0)
Sex
Female	1070 (84.4)	568 (41.2)
Male	166 (13.1)	805 (58.4)
Declined	32 (2.5)	5 (0.4)
Ethnicity
Caucasian	949 (74.9)	926 (67.2)
Native American	–	129 (9.4)
South East Asian	–	67 (4.9)
Mixed	104 (8.2)	71 (9.1)
Other	143 (11.3)	139 (10.1)
Declined	72 (5.7)	42 (3.0)
Marital Status
Single	520 (41.0)	542 (39.3)
Common-law/married	503 (39.7)	723 (52.5)
Divorced/separated	159 (12.5)	72 (5.2)
Other	38 (3.0)	11 (0.8)
Declined	48 (3.8)	11 (0.8)
Education
Less than high school	62 (4.9)	9 (0.7)
High school	68 (5.4)	99 (7.2)
Some college/university	211 (16.6)	292 (21.2)
College	85 (6.7)	258 (18.7)
Undergraduate	261 (20.6)	408 (29.6)
Graduate/Professional	524 (41.3)	303 (22.0)
Declined	57 (4.5)	6 (0.4)
Employment
Employed	728 (65.3)	1,165 (84.6)
Unemployed	186 (14.7)	116 (8.4)
Student	174 (13.7)	61 (4.5)
Other	28 (2.2)	13 (0.9)
Declined	52 (4.1)	23 (1.7)
Diagnosed mental health problem(s)
Current	647 (51.0)	385 (27.9)
Past	174 (13.7)	222 (16.1)
No	377 (29.7)	715 (51.9)
Declined	70 (5.5)	55 (4.0)

Figure 1. Percentage GPS item endorsement by gender and sample

F = Female, M = Male, GC-TS = Global Collaboration on Traumatic Stress. *Difference between F vs. M is statistically significant at p < .01 (2-tailed). For full statistical reporting please see the supplemental materials.

Table 2. Factor (pattern) loadings for the GPS

Have you ever …	GC-TS	MTurk	u^2 GC-TS	u^2 MTurk
1. Nightmares	.68	.76	.54	.42
2. Avoidance	.71	.61	.50	.63
3. Hypervigilance	.76	.72	.42	.49
4. Numbing/detachment	.86	.73	.27	.47
5. Guilt	.74	.76	.45	.42
6. Worthlessness	.82	.79	.33	.37
7. Anger Dyscontrol	.58	.66	.67	.57
8. Anxiety	.79	.68	.38	.54
9. Worrying	.75	.71	.44	.49
10. Depression	.84	.78	.30	.39
11. Anhedonia	.73	.80	.46	.37
12. Insomnia	.54	.52	.71	.73
13. Self-harm	.61	.58	.63	.66
14. Derealization	.67	.68	.55	.53
15. Depersonalization	.66	.71	.51	.50
16. Other problems	.68	.80	.54	.36
18. Substance Use	.50	.55	.75	.69

u² = uniqueness value.

Table 3. Comparison of females and males on GPS scale scores across two samples

	Female M (SD)	Male M (SD)	t (df)	p	d [95% CI]
GC-TS Sample
	(n = 1070)	(n = 166)
GPS symptoms	10.9 (4.4)	10. (4.8)	0.7 (1234)	.505	0.06 [–0.11, 0.22]
GPS risk score	3.2 (1.1)	3.1 (1.2)	0.6 (1234)	.531	0.06 [–0.11, 0.22]
MTurk Sample
	(n = 568)	(n = 805)
GPS symptoms	7.9 (5.0)	7.5 (4.8)	1.7 (1371)	.084	0.10 [–0.01, 0.20]
GPS risk score	2.5 (1.4)	2.2 (1.4)	3.1 (1371)	.002	0.18 [0.07, 0.28]

A positive d value indicates that the female participants in the samples scored higher on the scale.

Table 4. Correlations between the GPS and correlates

	GPS symptoms (17 items)	GPS risk factors (5 items)
LEQ (12 items)	.47	.42
LEC-5	.43	.38
ACE	.47	.46
PCL-5	.68	.56
TRASC	.52	.41
DPTSD	.48	.37
ITQ-PTSD-6	.60	.49
ITQ-CPTSD-6	.64	.54
M (SD) – GC-TS	10.9 (4.4)	3.2 (1.1)
M (SD) – MTurk	7.6 (4.9)	2.3 (1.4)

All p-values < .001. LES = . LEC-5 = Life Events Checklist for DSM-5. ACE = Adverse childhood experiences. PCL-5 = PTSD Checklist for DSM-5. TRASC = Trauma-related altered states of consciousness. DPTSD = Dissociative Subtype of PTSD items (derealization and depersonalization only). ITQ-PTSD-6 = the International Trauma Questionnaire PTSD items. ITQ-CPTSD-6 = ITQ Complex PTSD items.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author, PF, upon reasonable request.