Table 1.

Descriptive characteristics of study participants, dependent and independent variables of interest, IMPACT study, 2001–2003.

Variable	Number	Percent
BMI-for-age percentilesa     < 5th percentile     ≥5th to <85th percentile     ≥≥85th to <95th percentile     ≥≥ 95th percentile	717 28 510 105 74	4 71 15 10
Ethnicity     White     Hispanic     Black     Other	717 515 83 39 80	72 12 5 11
Onset of menses	140	20
	Mean (SD)	Range
Age (years)	11.6 (±0.4)	10–13
Calcium intake     Milligrams calcium consumed/day     Glasses of milk consumed/day	1321.3 (±754.8) 1.9 (±1.3)	154.3–5268.8 0–5
Bone quality     Calcaneus stiffness index (SI)	73.8 (±14.9)	34.7–130.1
Knowledge of:     Osteoporosis (% correct)     Calcium content of foods (% correct)	26.4 (±16.6) 66.1 (±16.3)	0–85.7 0–100
Self-efficacy towards calcium-rich foodsb Calcium outcome expectationsc	29.8 (±6.6) 17.9 (±2.9)	9–45 7–35
Milk availability at homed	3.8 (±0.5)	0–4

^aBody Mass Index- for-age percentile calculations and classifications are based on National Center for Health Statistics and National Center for Chronic Disease Prevention and Health Promotion growth charts with < 5th percentile = underweight, ≥5th to < 85th percentile = normal weight, ≥85th to <95th percentile = at overweight and ≥ 95th percentile = obese.

^bSelf-efficacy towards calcium-rich foods was measured using nine items on the COPA, with scores ranging from 1 to 5 for each item. These scores were then summed to develop the scale for self-efficacy with the lowest possible score being 9 and highest possible being 45.

^cCalcium outcome expectations was measured using seven items on the COPA, with scores ranging from 1 to 5 for each item. These scores were then summed to develop the scale for outcome expectations with the lowest possible score being 7 and highest possible being 35.

^dMilk availability at home was measured using one item, “Milk is available at my house”, with scores ranging from 0 (never) to 4 (All the time). Mean scores are presented.