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TABLE B-2 Estimates of Within-Subject Variation in Intake, Expressed as Standard Deviation (SD)a and Coefficient of Variation (CV) for Vitamins and Minerals in Adults Aged 19 and Over

Nutrientb

Adults Ages 19–50 y

Adults, Ages 51 y and Over

 

Females

(n = 2,480)c

Males

(n = 2,538)

Females

(n = 2,162)

Males

(n = 2,280)

   

CV

 

CV

 

CV

 

CV

 

SD

(%)

SD

(%)

SD

(%)

SD

(%)

Vitamin A (μg)

1,300

152

1,160

115

1,255

129

1,619

133

Carotene (RE)

799

175

875

177

796

147

919

153

Vitamin E (mg)

5

76

7

176

6

65

9

60

Vitamin C (mg)

73

87

93

92

61

69

72

71

Thiamin (mg)

0.6

47

0.9

46

0.5

41

0.7

40

Riboflavin (mg)

0.6

50

1.0

44

0.6

42

0.8

40

Niacin (mg)

9

47

12

44

7

42

9

39

Vitamin B6 (mg)

0.8

53

1.0

48

0.6

44

0.8

42

Folate (μg)d

131

62

180

61

12

52

150

53

Vitamin B12 (μg)

12

294

13

212

10

237

14

226

Calcium (mg)

325

51

492

54

256

44

339

44

Phosphorous (mg)

395

39

573

38

313

33

408

32

Magnesium (mg)

86

38

122

38

74

33

94

32

Iron (mg)

7

53

9

51

5

44

7

44

Zinc (mg)

6

61

9

63

5

58

8

66

Copper (mg)

0.6

53

0.7

48

0.5

53

0.7

56

Sodium (mg)

1,839

44

1,819

43

1,016

41

1,323

38

Potassium (mg)

851

38

1,147

36

723

31

922

31

NOTE: When the CV is larger than 60 to 70 percent the distribution of daily intakes is nonnormal and the methods presented here are unreliable.

a Square root of the residual variance after accounting for subject, and sequence of observation (gender and age controlled by classifications).

b Nutrient intakes are for food only, data does not include intake from supplements.

c Sample size was inadequate to provide separate estimates for pregnant or lactating women.

d Folate reported in μg rather than as the new dietary folate equivalents (DFE).

SOURCE: Data from Continuing Survey of Food Intakes by Individuals1994–1996.

certainty can be adjusted by either increasing or decreasing the value of the cutoff for D/SDD (e.g., if 0.5 or −0.5 was used, then the level of certainty would decrease to about 70 percent). Table B-1 indicates the probability, or level of certainty, of correctly concluding that the usual intake is adequate (or inadequate) when D/SDD ranges from 2.00 to −2.00.



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