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Table 1 Characteristics of early refusers, early consenters, and late/non-responders for enrollment into the Millennium Cohort Study

From: Demographic and occupational predictors of early response to a mailed invitation to enroll in a longitudinal health study

 

Early Refuser†

Early Consenter‡

Late/Non-responder§¶

 

N

%

N

%

N

%

Sex

      

Male

537

76.3

15,283

70.0

147,497

76.9

Female

167

23.7

6,537

30.0

44,370

23.1

Age quartile (years)

      

17–23

88

12.5

2,994

13.7

47,596

24.8

24–29

106

15.0

3,761

17.2

46,958

24.5

30–37

178

25.3

6,186

28.4

51,107

26.6

≥38

332

47.2

8,879

40.7

46,206

24.1

Education

      

No high school diploma

22

3.1

1,330

6.1

14,961

7.8

High school graduate

187

26.6

8,436

38.7

96,903

50.5

Some college

211

30.0

5,723

26.2

46,783

24.4

College graduate

147

20.9

3,874

17.7

22,953

12.0

Advanced degree

137

19.4

2,457

11.3

10,267

5.3

Marital status

      

Married

492

69.9

14,074

64.5

103,076

53.7

Not married

212

30.1

7,746

35.5

88,791

46.3

Race/ethnicity

      

White non-Hispanic

543

77.1

16,294

74.7

124,676

65.0

Black non-Hispanic

55

7.8

2,441

11.2

36,713

19.1

Hispanic

31

4.4

1,170

5.4

14,245

7.4

Asian/Pacific Islander

64

9.1

1,474

6.7

11,778

6.2

American Indian

6

0.9

194

0.9

1,731

0.9

Other

5

0.7

247

1.1

2,724

1.4

Service branch

      

Army

201

28.6

9.907

45.4

86,120

44.9

Air Force

326

46.3

6,849

31.4

55,576

29.0

Navy

146

20.7

3,809

17.5

35,313

18.4

Marine Corps

21

3.0

982

4.5

12,635

6.6

Coast Guard

10

1.4

273

1.2

2,223

1.1

Duty status

      

Active duty

313

44.5

9,734

44.6

103,069

53.7

Reserve/National Guard

391

55.5

12,086

55.4

88,798

46.3

Previous deployment experience #

      

Non-deployed

502

71.3

15,873

72.7

134,177

69.9

Deployed

202

28.7

5,947

27.3

57,690

30.1

Occupational category

      

Electrical/mechanical

80

11.4

2,923

13.4

31,798

16.6

Combat specialists

169

24.0

4,281

19.6

40,325

21.0

Electronic equipment repair

73

10.4

1,837

8.4

15,388

8.0

Communications/intelligence

39

5.5

1,481

6.8

12,827

6.7

Health care specialists

67

9.5

2,601

11.9

15,794

8.2

Other technical & allied specialists

12

1.7

580

2.7

4,722

2.4

Functional support specialists

158

22.4

4,562

20.9

34,713

18.1

Craft workers

23

3.3

700

3.2

6,852

3.6

Service and supply handlers

48

6.8

1,854

8.5

17,212

9.0

Trainees, other

35

5.0

1,001

4.6

12,236

6.4

  1. ** First enrollment into the Millennium Cohort Study.
  2. † Early refusers are invitees who communicated their unwillingness to participate in the study prior to 01 September 2001.
  3. ‡ Early consenters are invitees who completed an online or paper survey prior to 01 September 2001.
  4. § Late/non-responders are invitees who responded after 01 September 2001 or failed to respond in any manner.
  5. ¶ Differences between early refusers, early consenters, and late/non-responders were tested with the Pearson chi-square test of association. All p values were < 0.001.
  6. # Previous deployment experience to southwest Asia, Bosnia, or Kosovo between 1998 and 2001.
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BMC Medical Research Methodology

ISSN: 1471-2288

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