Psychometric properties of the Brief Symptom Inventory in nomophobic subjects: insights from preliminary confirmatory factor, exploratory factor, and clustering analyses in a sample of healthy Italian volunteers

Figures & data

Table 1 Scores obtained as mean and SD for each subscale of the Brief Symptom Inventory (BSI)

BSI subscale	Mean	SD	Different from norms for adult nonpatients
Anxiety	1.244	0.7936	P<0.001
Depression	1.225	0.8264	P<0.001
Hostility	0.978	0.8103	P<0.001
Interpersonal sensitivity	0.856	0.7986	P<0.001
Obsession–compulsion	0.884	0.7698	P<0.001
Phobic anxiety	0.931	0.8073	P<0.001
Paranoid ideation	1.101	0.8516	P<0.001
Psychoticism	1.239	0.8854	P<0.001
Somatization	0.945	0.8715	P<0.001

Note: Scores have been compared with norms for adult nonpatients.

Table 2 Reliability statistics for the Brief Symptom Inventory (BSI) among nomophobic subjects

BSI subscale	Cronbach’s alpha
Overall	0.972
Somatization	0.846
Obsession–compulsion	0.838
Interpersonal sensitivity	0.847
Depression	0.875
Anxiety	0.863
Hostility	0.810
Phobic anxiety	0.783
Paranoid ideation	0.808
Psychoticism	0.733

Table 3 Correlation analysis among the subscales of the Brief Symptom Inventory

		Anxiety	Depression	Hostility	Interpersonal sensitivity	Obsession–compulsion	Phobic anxiety	Paranoid ideation	Psychoticism
Depression	Correlation coefficient	0.736
	Significance level P	<0.0001
Hostility	Correlation coefficient	0.679	0.647
	Significance level P	<0.0001	<0.0001
Interpersonal sensitivity	Correlation coefficient	0.740	0.784	0.659
	Significance level P	<0.0001	<0.0001	<0.0001
Obsession–compulsion	Correlation coefficient	0.733	0.730	0.657	0.717
	Significance level P	<0.0001	<0.0001	<0.0001	<0.0001
Phobic anxiety	Correlation coefficient	0.736	0.639	0.568	0.689	0.651
	Significance level P	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
Paranoid ideation	Correlation coefficient	0.731	0.748	0.711	0.810	0.707	0.650
	Significance level P	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
Psychoticism	Correlation coefficient	0.724	0.786	0.646	0.767	0.728	0.723	0.778
	Significance level P	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
Somatization	Correlation coefficient	0.747	0.575	0.611	0.582	0.635	0.675	0.641	0.607
	Significance level P	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001

Table 4 Correlation analysis between the Brief Symptom Inventory (BSI) and the Nomophobia questionnaire

BSI subscale		Factor 1 (not being able to access information)	Factor 2 (giving up convenience/losing connectedness)	Factor 3 (not being able to communicate)	Total score
Anxiety	Correlation coefficient	0.237	0.291	0.243	0.314
	Significance level P	<0.0001	<0.0001	<0.0001	<0.0001
Depression	Correlation coefficient	0.222	0.335	0.180	0.281
	Significance level P	<0.0001	<0.0001	0.0003	<0.0001
Hostility	Correlation coefficient	0.184	0.278	0.169	0.241
	Significance level P	0.0002	<0.0001	0.0006	<0.0001
Interpersonal sensitivity	Correlation coefficient	0.221	0.342	0.200	0.291
	Significance level P	<0.0001	<0.0001	0.0001	<0.0001
Obsession–compulsion	Correlation coefficient	0.234	0.344	0.216	0.303
	Significance level P	<0.0001	<0.0001	<0.0001	<0.0001
Phobic anxiety	Correlation coefficient	0.115	0.340	0.138	0.230
	Significance level P	0.0208	<0.0001	0.0057	<0.0001
Paranoid ideation	Correlation coefficient	0.184	0.319	0.184	0.263
	Significance level P	0.0002	<0.0001	0.0002	<0.0001
Psychoticism	Correlation coefficient	0.133	0.323	0.137	0.229
	Significance level P	0.0073	<0.0001	0.0058	<0.0001
Somatization	Correlation coefficient	0.163	0.302	0.194	0.253
	Significance level P	0.0010	<0.0001	0.0001	<0.0001

Table 5 Multivariate regression analysis for the Global Severity Index of the Brief Symptom Inventory

Independent variable	Coefficient	Standard error	rpartial	t	P-value
(Constant)	0.7209
Factor 1 (not being able to access information)	−0.006034	0.006848	−0.04429	−0.881	0.3788
Factor 2 (giving up convenience/losing connectedness)	0.02877	0.005494	0.2548	5.236	<0.0001
Factor 3 (not being able to communicate)	−0.0003147	0.005557	−0.002850	−0.0566	0.9549
Hours	0.05288	0.02092	0.1262	2.528	0.0119
Schooling level	−0.09865	0.04485	−0.1100	−2.200	0.0284
Age	0.001618	0.004620	0.01762	0.350	0.7264
Gender	0.09083	0.07656	0.05959	1.186	0.2362

Table 6 Predictors for each subscale of the Brief Symptom Inventory

Construct	Predictor(s)
Anxiety	Factor 2 (giving up convenience/losing connectedness), hours, gender
Depression	Factor 2 (giving up convenience/losing connectedness), hours
Hostility	Factor 2 (giving up convenience/losing connectedness)
Interpersonal sensitivity	Factor 2 (giving up convenience/losing connectedness), hours, schooling level, gender
Obsession–compulsion	Factor 2 (giving up convenience/losing connectedness), schooling level
Phobic anxiety	Factor 1 (negative; not being able to access information), factor 2 (giving up convenience/losing connectedness)
Paranoid ideation	Factor 2 (giving up convenience/losing connectedness)
Psychoticism	Factor 2 (giving up convenience/losing connectedness), schooling level
Somatization	Factor 2 (giving up convenience/losing connectedness), hours, gender

Figure 1 General Severity Index (GSI) broken down according to the severity of nomophobia.

Table 7 The two clusters with their centers for each Brief Symptom Inventory (BSI) subscale

BSI subscale	Cluster
	1	2
Somatization	11.57	3.28
Obsession–compulsion	13.06	4.93
Interpersonal sensitivity	9.61	2.66
Depression	13.65	4.54
Anxiety	12.62	4.31
Hostility	9.79	3.77
Phobic anxiety	6.07	0.98
Paranoid ideation	10.93	3.92
Psychoticism	9.06	2.83

Table 8 Analysis of variance between the two clusters for each Brief Symptom Inventory (BSI) subscale

BSI subscale	Cluster		Error		F	P-value
	Mean square	Df	Mean square	Df
Somatization	6660.960	1	20.699	401	321.796	<0.001
Obsession–compulsion	6397.213	1	15.617	401	409.639	<0.001
Interpersonal sensitivity	4681.301	1	7.977	401	586.882	<0.001
Depression	8030.578	1	15.742	401	510.121	<0.001
Anxiety	6683.736	1	14.658	401	455.973	<0.001
Hostility	3513.816	1	11.990	401	293.071	<0.001
Phobic anxiety	2508.603	1	8.138	401	308.276	<0.001
Paranoid ideation	4767.526	1	10.655	401	447.451	<0.001
Psychoticism	3767.381	1	9.526	401	395.470	<0.001

Abbreviation: Df, degrees of freedom.

Table 9 Loading factors of the exploratory factor analysis

BSI subscale	Factor loading (second-order 9-factor)	Items	Factor loading (first-order 9-factor)	Factor loading (1-factor)
Anxiety	0.890	1	0.674	0.611
		12	0.819	0.713
		19	0.846	0.735
		38	0.773	0.711
		45	0.824	0.736
		49	0.671	0.649
Depression	0.868	9	0.638	0.579
		16	0.803	0.690
		17	0.834	0.725
		18	0.793	0.661
		35	0.807	0.699
		50	0.822	0.751
Hostility	0.802	6	0.666	0.643
		13	0.790	0.644
		40	0.805	0.577
		41	0.794	0.584
		46	0.709	0.553
Interpersonal sensitivity	0.882	20	0.842	0.731
		21	0.838	0.693
		22	0.834	0.718
		42	0.799	0.757
Obsession–compulsion	0.855	15	0.801	0.709
		26	0.700	0.630
		27	0.814	0.657
		32	0.733	0.683
		36	0.821	0.691
Paranoid ideation	0.885	4	0.686	0.584
		10	0.719	0.607
		24	0.803	0.735
		48	0.773	0.716
		51	0.775	0.641
Phobic anxiety	0.823	8	0.763	0.518
		28	0.751	0.463
		31	0.794	0.663
		43	0.785	0.714
		47	0.615	0.612
Psychoticism	0.883	3	0.624	0.475
		14	0.736	0.727
		34	0.512	0.404
		44	0.812	0.703
		53	0.801	0.720
Somatization	0.786	2	0.665	0.493
		7	0.674	0.546
		23	0.681	0.540
		29	0.758	0.634
		30	0.755	0.606
		33	0.717	0.525
		37	0.795	0.670

Abbreviation: BSI, Brief Symptom Inventory

Table 10 Fit indices of the confirmatory factor analysis for the overall Brief Symptom Inventory (BSI) questionnaire and for each subscale

Model	CFI	TLI	SRMR	RMSEA	RMSEA 90% CI		AIC	BIC	Exact fit
					Lower	Upper			χ^2	Df	P
First-order models
9-factor	0.820	0.806	0.058	0.071	0.068	0.073	53.829	54.561	3.279	1.091	<0.001
1-factor	0.747	0.736	0.063	0.082	0.079	0.085	54.581	54.973	4.186	1.127	<0.001
Second-order models
9-factor	0.851	0.833	0.047	0.063	0.060	0.065	57.837	58.633	3.188	1.232	<0.001
BSI subscales
Somatization	0.964	0.946	0.033	0.077	0.054	0.102	8.182	8.266	47.6	14	<0.001
Obsession–compulsion	0.982	0.970	0.025	0.065	0.034	0.097	7.141	7.213	24.2	9	0.004
Interpersonal sensitivity	0.960	0.879	0.031	0.184	0.129	0.246	4.871	4.919	29.3	2	<0.001
Depression	0.928	0.881	0.045	0.152	0.125	0.181	6.880	6.952	92.6	9	<0.001
Anxiety	0.959	0.931	0.036	0.109	0.082	0.139	6.785	6.857	52.3	9	<0.001
Hostility	0.925	0.851	0.048	0.156	0.120	0.195	5.888	5.948	54.0	5	<0.001
Phobic anxiety	0.962	0.925	0.034	0.103	0.067	0.143	5.186	5.246	26.4	5	<0.001
Paranoid ideation	0.980	0.960	0.025	0.077	0.038	0.119	6.078	6.138	16.9	5	0.005
Psychoticism	0.948	0.896	0.044	0.109	0.073	0.149	6.093	6.153	29.0	5	<0.001

Abbreviations: AIC, Akaike Information Criterion; BIC, Bayesian Information Criterion; CFI, Comparative Fit Index; Df, degrees of freedom; RMSEA, root mean square error of approximation; SRMR, standardized root mean square residual; TLI, Tucker–Lewis Index.