Challenging the role of social norms regarding body weight as an explanation for weight, height, and BMI misreporting biases: Development and application of a new approach to examining misreporting and misclassification bias in surveys

Table 1 Patterns of error in self-reported weight and height and their relative contributions to bias in BMI determined from self-reported values.

	Total				Normal Range
	N	%	BMI_D	Relative Contribution to BMI_D	N	%	BMI_D	Relative Contribution to BMI_D
TOTAL	1942	100.0	-1.34		689	100.0	-0.49
Accurate Weight
Accurate Height	389	20.0	-0.17	-2.5	194	28.2	-0.16	-9.2
Under-reported Height	77	4.0	1.06	3.2	43	6.2	1.00	12.7
Over-reported Height	321	16.6	-1.48	-18.3	110	16.0	-1.12	-36.5
Over-reported Weight
Accurate Height	92	4.7	1.42	5.0	51	7.4	1.31	19.8
Under-reported Height	24	1.2	3.01	2.7	14	2.0	3.28	13.6
Over-reported Height	96	4.9	0.00	0.0	52	7.5	0.15	2.3
Under-reported Weight
Accurate Height	418	21.5	-1.92	-30.8	113	16.4	-1.45	-48.5
Under-reported Height	103	5.3	-0.53	-2.1	36	5.2	-0.19	-2.0
Over-reported Height	422	21.7	-3.54	-57.3	76	11.0	-2.34	-52.7
	Overweight				Obese, Classes I-III
	N	%	BMI _D	Relative Contribution to BMI _D	N	%	BMI _D	Relative Contribution to BMI _D
TOTAL	764	100.0	-1.33		474	100.0	-2.66
Accurate Weight
Accurate Height	147	19.2	-0.19	-2.7	46	9.7	-0.21	-0.8
Under-reported Height	29	3.8	1.16	3.3	3	0.6	0.96	0.2
Over-reported Height	149	19.5	-1.63	-23.9	56	11.8	-1.95	-8.7
Over-reported Weight
Accurate Height	27	3.5	1.43	3.8	13	2.7	1.89	1.9
Under-reported Height	7	0.9	2.75	1.9	2	0.4	-	-
Over-reported Height	27	3.5	-0.22	-0.6	15	3.2	-0.23	-0.3
Under-reported Weight
Accurate Height	184	24.1	-1.75	-31.7	121	25.5	-2.61	-25.0
Under-reported Height	31	4.1	-0.62	-1.9	35	7.4	-0.84	-2.3
Over-reported Height	163	21.3	-3.00	-48.1	183	38.6	-4.53	-65.7

BMI_D = BMI_SR - BMI_M (calculated for each subject, reported as mean values in table).
Self-reported height and weight were considered to be accurate when within ± 2.0 kg of measured weight or ± 2.0 cm of measured height.
Normal Range, BMI 18.5-24.9 kg/m²; Overweight, BMI 25.0-29.9 kg/m²; Obese, Class I-III, BMI ≥ 30.0 kg/m².
Relative Contribution to BMI_D = [(N_ErrorType*Mean_ErrorType)/(N_total *Mean_total)]*100b, where b = -1 when BMI_D is negative and b = 1 when BMI_D is positive to account for the type's direction of bias.

ISSN: 1471-2458