Validity of self-reported weight, height and resultant body mass index in Chinese adolescents and factors associated with errors in self-reports

Table 2 Self-reported and measured weight, height and BMI among adolescents, Xi'an, China

Items	Weight(kg)	Height(cm)	BMI(kg/m²)
Measured value (mean ± S.D.)	50.5 ± 10.9	158.7 ± 8.4	19.9 ± 3.1
Reported value (mean ± S.D.)	48.2 ± 10.3	160.1 ± 8.7	18.7 ± 3.0
Pearson's correlation ^a	0.912	0.935	0.809
Intraclass correlation	0.85	0.898	0.796
Weighted Kappa ^{a, b}	0.86	0.91	0.75
95% confidence interval	0.84, 0.88	0.90, 0.92	0.74, 0.76
Mean difference ^{a, c}	-2.35	1.36	-1.23
95% confidence interval	-2.56, -2.14	1.21, 1.51	-1.32, -1.14
Mean absolute difference ^a	3.36	2.43	1.64
95% confidence interval	3.19, 3.54	2.31, 2.54	1.56, 1.71

^a Between reported data and measured data.
^b Weight, height and BMI values were ranked and divided into quintiles, and quadratic weighted Kappa statistics are presented.
^c Reported data minus measured data.

ISSN: 1471-2458