Table 4 Detailed Reasons for Baseline Non-participation Stated in 2009 or 2010^a by Non-participants (n = 786)

Refusal to participate in scientific studies on principle

1

1

2

42.1

37.2

53.4

31.1

Too ill

2

2

2

31.4

38.3

24.9

31.1

No interest in this study

3

3

1

25.8

16.1

25.9

41.5

No time^b

4

4

4

12.5

18.1

7.5

11.5

Limited knowledge of German^b

5

5

5

4.6

0.7

5.9

8.7

Dementia

6

11

6

3.1

3.4

1.0

6.0

Miscellaneous^b

7

7

9

2.7

2.3

3.9

1.1

Too old^b

7

7

9

2.7

4.0

2.3

1.1

Participation too strenuous^b

9

5

 -

2.5

4.7

2.0

0.0

Family member too ill/ in need of care^b

10

10

13

1.9

3.7

1.0

0.5

Hospital stay

10

9

 -

1.9

2.3

2.6

0.0

Hearing/visual impairment

12

12

9

1.7

2.0

1.6

1.1

Personal reasons (not otherwise specified)^b

13

13

 -

1.1

1.7

1.3

0.0

Having sufficient medical care^b

13

13

 -

1.1

2.7

0.3

0.0

Having no personal benefit^b

15

15

 -

1.0

0.7

2.0

0.0

Too healthy

16

16

 -

0.9

2.0

0.3

0.0

Death of a family member^b

16

16

 -

0.9

1.3

1.0

0.0

Speech disorder

16

19

9

0.9

1.0

0.7

1.1

Being in residential care in 2009

16

25

7

0.9

0.0

0.3

3.3

Too busy^b

20

18

 -

0.8

1.3

0.7

0.0

Being absent during recruitment period^b

21

-

8

0.6

0.0

0.0

2.7

Participating in another scientific study^b

22

20

13

0.5

0.3

0.7

0.5

Being in rehabilitation

23

20

 -

0.4

0.7

0.3

0.0

Being unmotivated^b

23

20

 -

0.4

0.7

0.3

0.0

Bad experiences with scientific studies^b

23

20

 -

0.4

0.0

1.0

0.0

Having concerns about the study’s risks^b

26

24

 -

0.3

0.3

0.3

0.0