Table 1

Demographic and Health Characteristics by Incentive Condition

Characteristics

$2 incentive %(n)

$5 incentive %(n)

p-value


Age*

< 50

34.29 (228)

30.32 (201)

0.1924

50-75

33.53 (223)

33.18 (220)

0.8867

> 75

32.18 (214)

36.50 (242)

0.1898

Race*

Caucasian

68.57 (456)

68.78 (456)

1.000

African American

15.79 (105)

17.65 (117)

0.4206

Other

15.64 (104)

13.57 (90)

0.3148

Sex*

Female

18.95 (126)

13.88 (92)

0.0213

Male

81.05 (539)

86.12 (571)

0.3368

Education**

Grade 11 or less

15.96 (64)

21.32 (87)

0.0612

High school grad

30.42 (122)

33.58 (137)

0.8687

Some college/tech deg

33.92 (136)

27.21 (111)

0.1117

College grad

14.21 (57)

13.24 (54)

0.7758

Post grad (MS, PhD)

5.49 (22)

4.66 (19)

0.6394

Income***

Under $20,000

50.76 (201)

50.00 (192)

0.6498

$20,000-40,000

31.31 (124)

31.25 (244)

0.7979

$40,000-$60,000

10.86 (43)

11.98 (46)

0.7505

Over $60,000

7.07 (28)

6.77 (26)

0.7855

Marital Status*

Married/Living with Someone

54.44 (362)

54.75 (363)

0.9704

Not Married

45.56 (303)

45.25 (300)

0.9028

Charlson comorbidity score*

0

46.17 (307)

42.23 (280)

0.2651

1

20.30 (135)

22.47 (284)

0.4061

2+

33.53 (223)

35.29 (234)

0.6069

Mental health diagnoses*

No mental health diagnosis

46.32 (308)

47.66 (316)

0.7488

Substance abuse only

8.72 (58)

8.75 (58)

1.000

Psychiatric only

28.27 (188)

26.85 (178)

0.6012

Dual diagnosis

16.69 (111)

16.74 (111)

1.000

Rural/Urban Status*

Urban

94.89 (631)

90.80 (602)

0.4089

Rural

5.11 (34)

9.20 (61)

0.0056


*Data available for full study sample (N for $2 = 665; N for $5 = 663)

**Data only available from ancillary survey respondents(N for $2 = 401; N for $5 = 408)

***Data only available from ancillary survey respondents (N for $2 = 396; N for $5 = 384)

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

Open Data