The mother–daughter Shared Agency in Weight Management Scale (SAWMS): development, validation, and implications for body dissatisfaction

Table 2 Item Response theory parameter estimates and item-subscale correlation for the SAWM Scale

Subscale	Item	Item parameter estimates						Item-subscale correlation
Subscale	Item	a	b₁	b₂	b₃	b₄	b₅	Item-subscale correlation
Maternal control	SAWM1*	2.54	− 0.70	− 0.08	0.28	0.95	1.58	0.79
	SAWM2*	2.18	− 0.62	0.03	0.45	1.19	1.94	0.76
	SAWM3*	2.60	− 0.27	0.45	0.86	1.49	2.26	0.78
	SAWM4*	3.34	− 0.51	0.08	0.40	1.02	1.59	0.84
	SAWM5	1.96	− 1.10	− 0.40	0.04	0.85	1.80	0.75
	SAWM7	1.55	− 0.63	0.35	0.96	2.02	2.75	0.66
Maternal autonomy support	SAWM9*	2.79	− 1.73	− 0.98	− 0.42	0.41	1.31	0.78
	SAWM10*	2.29	− 1.71	− 1.01	− 0.53	0.28	1.11	0.76
	SAWM12*	2.86	− 1.86	− 1.34	− 0.92	− 0.21	0.61	0.78
	SAWM13	0.89	− 2.02	− 0.83	− 0.03	0.90	2.45	0.57
	SAWM14	1.03	− 2.85	− 1.61	− 0.72	0.30	1.77	0.60
	SAWM15*	2.05	− 1.64	− 0.93	− 0.37	0.43	1.31	0.76
Maternal collaboration	SAWM6*	2.94	− 0.80	− 0.03	0.42	1.20	2.06	0.87
	SAWM8*	3.83	− 0.68	0.02	0.45	1.30	1.96	0.88
	SAWM11*	2.13	− 1.19	− 0.36	0.15	1.03	1.95	0.85

Coefficients in bold indicate that items were retained in the version of the mother-daughter SAWMS after IRT analysis
a = discrimination parameter; b = estimated item difficulties corresponding to a 50% chance of choosing the response that is ≥ the subscript + 1; *selected item for inclusion in final subscales

ISSN: 2050-2974