TABLE 3.

Standardized regression coefficients (± SE) and coefficient of determination (R²) for the agreement between age- and sex-specific Z-scores for percentage body fat (%BF) and individual anthropometric measures in 8–19-y-old US children, by sex and race-ethnicity: NHANES 2001–2004^1,2

	Both sexes	Boys				Girls
	(n = 5355)	All races (n = 2792)	Whites (n = 796)	Blacks (n = 962)	Mexican Am. (n = 818)	All races (n = 2563)	Whites (n = 742)	Blacks (n = 809)	Mexican Am. (n = 809)
BMI Z-score	0.80 ± 0.01a (0.64)	0.79 ± 0.02a (0.62)	0.79 ± 0.03a (0.65)	0.83 ± 0.02 (0.58)	0.73 ± 0.02†a (0.66)	0.82 ± 0.02 (0.67)	0.82 ± 0.03 (0.69)	0.88 ± 0.02 (0.68)	0.77 ± 0.02† (0.68)
WC Z-score	0.82 ± 0.01ab (0.67)	0.83 ± 0.01ab (0.68)	0.83 ± 0.02a (0.69)	0.86 ± 0.01 (0.64)	0.79 ± 0.03ab (0.71)	0.82 ± 0.02 (0.66)	0.81 ± 0.03 (0.66)	0.85 ± 0.03 (0.69)	0.79 ± 0.02 (0.68)
WHtR Z-score	0.85 ± 0.01b (0.72)	0.86 ± 0.01b (0.73)	0.84 ± 0.02a (0.72)	0.87 ± 0.02 (0.69)	0.86 ± 0.03b (0.76)	0.84 ± 0.02 (0.70)	0.82 ± 0.02 (0.70)	0.84 ± 0.02 (0.71)	0.84 ± 0.02 (0.71)
TSF Z-score	0.89 ± 0.01c (0.79)	0.91 ± 0.01c (0.83)	0.90 ± 0.01c (0.83)	0.90 ± 0.02 (0.81)	0.88 ± 0.02c (0.83)	0.86 ± 0.01‡ (0.74)	0.86 ± 0.02 (0.75)	0.87 ± 0.02 (0.77)	0.84 ± 0.03 (0.74)

Abbreviations: BMI, body mass index; R², coefficient of determination; TSF, triceps skinfold thickness; WC, waist circumference; WHtR, waist-to-height ratio.

¹Age- and sex-specific Z-scores were estimated using the LMS curve-fitting procedure based on the NHANES 2001–2004 population.

²Data were weighted to represent the 40 million US children. All coefficients differ from zero (P < 0.001).

^*Differed from whites within sex

^†differed from blacks within sex

^‡differed from boys within race-ethnicity (P < 0.05; t-test).

^aValues in a subgroup (e.g., by sex and racial-ethnic group) with different superscript letters (a, b, or c) were significantly different (P < 0.05; t-test); a group without the letters indicates no difference (P ≥ 0.05; t-test).

^bValues in a subgroup (e.g., by sex and racial-ethnic group) with different superscript letters (a, b, or c) were significantly different (P < 0.05; t-test); a group without the letters indicates no difference (P ≥ 0.05; t-test).

^cValues in a subgroup (e.g., by sex and racial-ethnic group) with different superscript letters (a, b, or c) were significantly different (P < 0.05; t-test); a group without the letters indicates no difference (P ≥ 0.05; t-test).