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Table 2 Duration between mailing date of the invitation and active response

From: Study invitations with envelopes made from recycled paper do not increase likelihood of active responses or study participation in the German National Cohort

 

Mean

sd

ßa,b (95% CI)

Envelope color

 White

7.5

3.1

0

 Grey

7.4

3.2

0.65 (− 0.38, 1.68)

Sexc

 Female

7.4

3.0

0

 Male

7.4

3.3

0.06 (− 0.92, 1.04)

Nationalityc

 Non-German

8.2

3.2

0

 German

7.4

3.2

− 0.56 (− 2.59, 1.47)

Age

 20–29

7.4

2.9

− 0.53 (− 2.45, 1.39)

 30–39

6.8

2.8

− 0.66 (− 3.4, 2.08)

 40–49

7.5

2.8

0

 50–59

8.0

3.6

0.53 (− 0.71, 1.77)

 60–69

6.8

3.1

− 0.74 (− 2.03, 0.54)

N

171

  
  1. CI confidence interval
  2. aIncludes subjects who replied by letter, phone call, e-mail or visited the study center in person
  3. bAdjusted for pre-trial likelihood of active responses to invitation letter stratified by weekdays
  4. cInformation provided by Bremen’s resident registration office
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BMC Research Notes

ISSN: 1756-0500

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