Table 4

Representativeness of Responders on Demographic Characteristics

$2 incentive

$5 Incentive

Characteristics

Ancillary study population

$2 incentive population

1st Mailing

2nd Mailing

$5

incentive population

1st Mailing

2nd Mailing

(N = 1328)

(N = 665)

(N = 317)

(N = 435)

(N = 663)

(N = 383)

(N = 446)


Age

xx

xx

xx

xx

< 50

32.30 (429)

34.29 (228)

23.03 (73)

25.98 (113)

30.32 (201)

21.67 (83)

22.65 (101)

50-75

33.36 (443)

33.53 (223)

38.49 (122)

36.55 (159)

33.18 (220)

36.03 (138)

35.87 (160)

> 75

34.34 (456)

32.18 (214)

38.49 (122)

37.47 (163)

36.50 (242)

42.30 (162)

41.48 (185)

Race

xx

xx

xx

xx

Caucasian

68.67 (912)

68.57 (456)

83.91 (266)

81.84 (356)

68.78 (456)

81.46 (312)

79.82 (356)

African American

16.72 (222)

15.79 (105)

10.09 (32)

12.64 (55)

17.65 (117)

13.58 (52)

14.80 (66)

Other

14.61 (194)

15.64 (104)

5.99 (19)

5.52 (24)

13.57 (90)

4.96 (19)

5.38 (24)

Sex

x

xx

xx

Female

16.42 (218)

18.95 (126)

12.62 (40)

16.32 (71)

13.88 (92)

9.92 (38)

10.54 (47)

Male

83.58 (1110)

81.05 (539)

87.38 (277)

83.68 (364)

86.12 (571)

90.08 (345)

89.46 (399)

Marital Status

x

xx

xx

xx

Married/Living with Someone

54.59 (725)

54.44 (362)

60.57 (192)

60.23 (262)

54.75 (363)

66.06 (253)

62.33 (278)

Not Married

45.41 (603)

45.56 (303)

39.43 (125)

39.77 (173)

45.25 (300)

33.94 (130)

37.67 (168)

Charlson comorbidity score

0

44.20 (587)

46.17 (307)

42.59 (135)

42.53 (185)

42.23 (280)

38.64 (148)

39.69 (177)

1

21.39 (284)

20.30 (135)

18.93 (60)

20.00 (87)

22.47 (284)

21.67 (83)

22.20 (99)

2+

34.41 (457)

33.53 (223)

38.49 (122)

37.47 (163)

35.29 (234)

39.69 (152)

38.12 (170)

Mental health diagnoses

No mental health diagnosis

46.99 (624)

46.32 (308)

53.00 (168)

50.11 (218)

47.66 (316)

51.70 (198)

51.35 (229)

Substance abuse only

8.73 (116)

8.72 (58)

7.57 (24)

8.05 (35)

8.75 (58)

8.88 (34)

8.97 (40)

Psychiatric only

27.56 (366)

28.27 (188)

25.55 (81)

28.05 (122)

26.85 (178)

25.85 (99)

25.56 (114)

Dual diagnosis

16.72 (222)

16.69 (111)

13.88 (44)

13.79 (60)

16.74 (111)

13.58 (52)

14.13 (63)

Rural/Urban Status

xx

xx

Urban

92.85 (1233)

94.89 (631)

92.43 (293)

94.02 (409)

90.80 (602)

87.99 (337)

88.34 (394)

Rural

7.15 (95)

5.11 (34)

7.57 (24)

5.98 (26)

9.20 (61)

12.01 (46)

11.66 (52)


x p < 0.10 from overall non-responder population

xx p < 0.05 from overall non-responder population

Griffin et al. BMC Medical Research Methodology 2011 11:81   doi:10.1186/1471-2288-11-81

Open Data