TABLE 2-7a Illustrative, Approximate Relative Standard Errors (Coefficients of Variation, or CVs) for an Estimate of 15 Percent Poor School-Age Children from the ACS and the 2000 Census Long-Form Sample, by Population Size of Area

Population Size of Area (1)

Children Ages 5–17

ACS 1-Year Period Estimate

ACS 3-Year Period Estimate

ACS 5-Year Period Estimate

2000 Long-Form Sample Estimate

Total (20% of total pop.) (2)

Poor (15% of ages 5–17) (3)

CV(%) (4a)

(Sample Cases) (4b)

CV(%) (5a)

(Sample Cases) (5b)

CV(%) (6a)

(Sample Cases) (6b)

CV(%) (7a)

(Sample Cases) (7b)

2,500,000

500,000

75,000

3.8 %

(7,900)

2.2 %

(23,700)

1.7 %

(39,550)

1.1 %

(77,500)

1,000,000

200,000

30,000

6.0

(3,150)

3.5

(9,500)

2.7

(15,800)

1.8

(31,000)

500,000

100,000

15,000

8.5

(1,600)

4.9

(4,750)

3.8

(7,900)

2.5

(15,550)

250,000

50,000

7,500

12.1

(800)

7.0

(2,350)

5.4

(3,950)

3.6

(7,750)

100,000

20,000

3,000

19.1

(300)

11.0

(950)

8.5

(1,600)

5.6

(3,100)

65,000

13,000

1,950

23.7

(200)

13.6

(600)

10.6

(1,050)

7.0

(2,000)

50,000

10,000

1,500

27.0

(150)

15.6

(450)

12.1

(800)

8.0

(1,550)

25,000

5,000

750

38.2

(80)

22.0

(250)

17.1

(400)

11.3

(800)

20,000

4,000

600

42.7

(60)

24.6

(200)

19.1

(300)

12.6

(600)

10,000

2,000

300

60.4

(30)

34.8

(90)

27.0

(150)

17.9

(300)

5,000

1,000

150

85.4

(20)

49.2

(50)

38.1

(100)

25.2

(150)

3,000

600

90

95.6

(10)

55.0

(40)

42.7

(80)

28.3

(150)

1,500

300

45

72.8

(10)

41.9

(40)

32.5

(70)

21.5

(150)

500

100

15

100.2

(10)

57.7

(20)

44.7

(30)

37.3

(50)

NOTES: The coefficient of variation (CV) is the standard error (SE) of an estimate expressed as a percentage of the estimate (see Box 2-5). CVs that indicate often acceptable levels of precision are in bold italics. ACS estimates are not published below the solid line in column 4 (below 65,000 people) and column 6 (below 20,000 people).

Column 1: Assumed population size of an area.

Column 2: Assumed number of school-age children (ages 5–17); assumed to be 20 percent of column 1.

Column 3: Assumed number of poor school-age children; assumed to be 15 percent of column 2.

Column 4a: ACS 1-year period estimate CV; based on SE estimated as 2.24 times ACS 5-year period estimate SE (see column 6a).



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