Validation of the Inventory of Interpersonal Problems (IIP-64): a comparison of Swedish female outpatients with anorexia nervosa or bulimia nervosa and controls

Figures & data

Table 1. Demographic and clinical characteristics of the clinical samples (AN and BN) and the controls (C).

	AN^a (n = 74)	BN^b (n = 85)	C^c (n = 242)
	M (SD)	M (SD)	M (SD)	F
Age	18.9 (1.9)	20.8 (2.0)	21.1 (2.0)	34.440****
Demographic characteristics	N (%)	N (%)	N (%)	χ^2
Civic status (single)	53 (72)	58 (69)	116 (49)	18.072****
Housing				50.672****
With parents	56 (76)	30 (35)	78 (32)
Alone	6 (8)	31 (37)	64 (27)
With friends/partner	12 (16)	24 (28)	98 (41)
Highest education level				43.044****
Elementary school	40 (54)	18 (21)	43 (18)
High school	32 (43)	61 (72)	167 (70)
Higher education	2 (3)	6 (7)	30 (13)
Clinical characteristics
Experience of ED treatment				102.524****
No	34 (47)	47 (55)	224 (93)
Yes, former	22 (31)	30 (35)	11 (5)
Yes, current	16 (22)	8 (9)	5 (2)

^a Missing data: n = 2 (experience of ED treatment).

^b Missing data: n = 1 (civic status).

^c Missing data: n = 4 (civic status), n = 2 (housing) and n = 2 (experience of ED treatment).

**** p < .0001.

Table 2. Values of Cronbach’s alpha (α) of IIP-64, total scale and subscales, in patients with and ED and total group.

	ED patients (n = 159)	Total group (n = 401)
IIP-64 total scale	0.93	0.94
IIP-64 subscales
Domineering/controlling	0.67	0.71
Vindictive/self-centered	0.71	0.73
Cold/distant	0.77	0.81
Socially inhibited	0.87	0.87
Non-assertive	0.91	0.89
Overly accommodating	0.80	0.81
Self-sacrificing	0.78	0.81
Intrusive/needy	0.72	0.71

Figure 1. Component plot of PCAs with varimax rotation based on ipsatized subscale scores in the ED sample (dots) and controls (triangles). PA: domineering/controlling; BC: vindictive/self-centered; DE: cold/distant; FG: socially inhibited; HI: non-assertive; JK: overly accommodating; LM:  self-sacrificing; NO: intrusive/needy.

Table 3. Bivariate correlations of IIP-64 subscales and EDI-3 composite scales in the ED sample, based on raw scores and ipsatized scores (in parenthesis).

	EDI-3 composite scales
	ED risk	Ineffectiveness	Interpersonal problems	Affective problems	Over control
IIP-64 subscales
Domineering/controlling	.00/(−.28)	.22/(−.35*)	.23/(−.34*)	.45*/(.01)	.32*/(−.09)
Vindictive/self-centered	.19/(−.09)	.38*/(−.19)	.55*/(.00)	.45*/(.05)	.34*/(−.07)
Cold/distant	.28/(.05)	.48*/(.00)	.71*/(.30*)	.41*/(.07)	.41*/ (.09)
Socially inhibited	.27/(.14)	.60*/(.37*)	.76*/(.61*)	.28/(.02)	.31*/(.09)
Non-assertive	.32*/(.21)	.58*/(.36*)	.50*/(.24)	.24/(-.01)	.27/(.05)
Overly accommodating	.24/(.05)	.40*/(.00)	.32*/(−.13)	.22/(−.12)	.25/(−.06)
Self-sacrificing	.13/(−.10)	.31*/(−.12)	.21/(−.26)	.23/(−.09)	.24/(−.06)
Intrusive/needy	.22/(−.02)	.31*/(−.17)	.10/(−.42*)	.42*/(.09)	.37*/(.05)

For the sake of clarity, correlations above .30 are marked with an asterisk (*).

Table 4. One-way analysis of variance (ANOVA) and differences of means (M), standard deviations (SD) and effect sizes (Cohen’s d) for patients with AN, BN and controls (C).

	AN (n = 74) M (SD)	BN (n = 85) M (SD)	C (n = 242) M (SD)	F	P^a	AN vs CCohen’s d^b	BN vs CCohen’s d^b
IIP-64 total scale	72.55 (29.34)	78.19 (30.98)	49.19 (26.67)	42.986^*^*^**	AN, BN > NC	.83	1.00
IIP-64 subscales
Domineering/controlling	5.35 (4.78)	5.32 (3.87)	3.56 (3.71)	9.728*	AN, BN > NC	.42	.46
Vindictive/self-centered	5.69 (4.26)	7.07 (4.69)	3.81 (3.66)	22.794*	AN, BN > NC	.47	.77
Cold/distant	6.76 (4.65)	8.14 (5.54)	4.34 (4.71)	21.534*	AN, BN > NC	.52	.74
Socially inhibited	10.07 (6.37)	10.52 (7.47)	5.56 (5.10)	31.044*	AN, BN > NC	.78	.78
Non-assertive	13.23 (7.58)	13.36 (7.63)	7.65 (5.52)	37.050*	AN, BN > NC	.84	.86
Overly accommodating	12.36 (6.29)	13.51 (6.09)	9.37 (5.68)	18.775*	AN, BN > NC	.50	.70
Self-sacrificing	11.99 (6.65)	11.73 (5.72)	8.09 (5.97)	18.553*	AN, BN > NC	.62	.62
Intrusive/needy	7.11 (5.52)	8.53 (5.29)	6.81 (4.76)	3.730	NS	.06	.34

* p < .0001.

^a Post-hoc: Tukey.

^b .20 = small effect, .50 = medium effect, .80 = large effect.