Table 4. Results from logit regression models of respondent weight underestimation (log-odd estimates and s.e.).

Weight underestimation	Model I				Model II				Model III
	Women		Men		Women		Men		Women		Men
	Coef.	s.e.	Coef.	s.e.	Coef.	s.e.	Coef.	s.e.	Coef.	s.e.	Coef.	s.e.
Constant	−7.012	1.33***	−5.795	0.94***	−7.032	1.36***	−5.752	0.93***	−6.991	1.36***	−5.693	0.94***
BMI	0.217	0.03***	0.197	0.03***	0.218	0.03***	0.197	0.03***	0.216	0.03***	0.198	0.03***
Age (years)	−0.027	0.03	0.013	0.02	−0.029	0.03	0.013	0.02	−0.030	0.03	0.010	0.02
Primary education	Referent		Referent		Referent		Referent		Referent		Referent
Secondary education	−0.342	0.41	−0.275	0.23	−0.353	0.41	−0.274	0.23	−0.387	0.41	−0.286	0.23
Vocational education	−0.441	0.46	−0.258	0.27	−0.461	0.45	−0.261	0.27	−0.452	0.46	−0.286	0.27
Short-term higher education	−0.259	0.44	−0.097	0.33	−0.282	0.44	−0.107	0.33	−0.237	0.44	−0.097	0.33
Middle-term higher education	−0.509	0.44	−0.353	0.27	−0.517	0.44	−0.357	0.26	−0.544	0.45	−0.365	0.26
Long-term higher education	−0.841	0.49+	−1.156	0.43***	−0.852	0.49+	−1.169	0.43***	−0.884	0.49+	−1.150	0.43***
Relationship status	0.528	0.28+	0.065	0.17	0.525	0.28+	0.067	0.17	0.553	0.28*	0.068	0.17
Age difference <6 years	0.077	0.17	−0.018	0.14	0.090	0.17	−0.022	0.14	0.082	0.17	−0.007	0.14
Grew up together	0.035	0.25	−0.142	0.17	0.017	0.24	−0.145	0.17	−0.001	0.23	−0.157	0.17
Number of siblings	0.087	0.18	−0.133	0.11	0.088	0.17	−0.133	0.11	0.058	0.16	−0.130	0.11
Brother	0.185	0.18	0.170	0.13	0.117	0.19	0.154	0.13	0.324	0.23	0.069	0.16
Sibling BMI	−0.001	0.02	−0.024	0.02	−0.014	0.02	−0.026	0.02	−0.030	0.03	−0.061	0.02***
Sibling BMI*brother									0.025	0.04	0.070	0.03*
Sibling underestimation					0.395	0.27	−0.007	0.21	1.098	0.52*	0.026	0.31
Sibling underestimation*brother									−1.170	0.61+	0.176	0.45
Sibling overestimation					−0.222	0.42	−0.329	0.27	−0.778	0.56	−0.576	0.30+
Sibling overestimation*brother									1.209	0.84	0.529	0.56
Number of observations	1524		1444		1524		1444		1524		1444
Log likelihood	−471.63		−759.72		−469.68		−759.03		−463.93		−754.91

Abbreviations: BMI, body mass index (calculated as kg m⁻²); Coef, coefficient.

Significance level: + at 10%, * at 5%, ** at 1%, *** at 0.01%. Standard errors are adjusted for sibling clustering.