TABLE 2-8 Illustrative, Approximate Relative Standard Errors (Coefficients of Variation, or CVs) for an Estimate of 15 Percent Poor People from the ACS and the 2000 Census Long-Form Sample, by Population Size of Area

Population Size of Area (1)

Poor People (15% of total pop.) (2)

ACS 1-Year Period Estimate

ACS 3-Year Period Estimate

ACS 5-Year Period Estimate

2000 Long-Form-Sample Estimate

CV(%) (3a)

(Sample Cases) (3b)

CV(%) (4a)

(Sample Cases) (4b)

CV(%) (5a)

(Sample Cases) (5b)

CV(%) (6a)

(Sample Cases) (6b)

2,500,000

375,000

1.7

%(39,550)

1.0%

(118,600)

0.8%

(197,650)

0.5%

(387,500)

1,000,000

150,000

2.7

(15,800)

1.6

(47,450)

1.2

(79,050)

0.8

(155,000)

500,000

75,000

3.8

(7,900)

2.2

(23,700)

1.7

(39,550)

1.1

(77,500)

250,000

37,500

5.4

(3,950)

3.1

(11,850)

2.4

(19,750)

1.6

(38,750)

100,000

15,000

8.5

(1,600)

4.9

(4,750)

3.8

(7,900)

2.5

(15,500)

65,000

13,000

10.6

(1,050)

6.1

(3,100)

4.7

(5,150)

3.1

(10,100)

50,000

7,500

12.1

(800)

7.0

(2,350)

5.4

(4,050)

3.6

(7,750)

25,000

3,750

17.1

(400)

9.8

(1,200)

7.6

(2,000)

5.1

(3,900)

20,000

3,000

19.1

(300)

11.0

(950)

8.5

(1,600)

5.6

(3,100)

10,000

1,500

27.0

(150)

15.6

(450)

12.1

(800)

8.0

(1,550)

5,000

750

38.2

(80)

22.0

(250)

17.1

(400)

11.3

(800)

3,000

450

42.7

(70)

24.6

(200)

19.1

(350)

12.6

(700)

1,500

225

32.5

(70)

18.7

(200)

14.5

(350)

9.6

(700)

500

75

44.8

(30)

25.8

(100)

20.0

(150)

16.7

(250)

NOTES: See Notes for Table 2-7a—columns 3a–6b in Table 2-8 correspond to columns 4a–7b, respectively, in Table 2-7a. Population sizes for calculating standard errors are in column 1. To obtain an approximate 90 percent margin of error, multiply 15 percent by the estimated coefficient of variation (CV) above to obtain the estimated standard error and multiply the result by 1.65. For example, the 90 percent margin of error for an ACS 1-year period estimate of 15 percent poor people in an area of 65,000 total population is 15 times 0.106 equals 1.6, times 1.65 equals ±2.6, which, in turn, gives a 90 percent confidence interval of 12.4–17.6 percent poor people.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement