Table 2 Developing choice sets

Methods for attributes and levels selection

Literature review, expert’s opinion

3

Literature review, expert’s opinion, qualitative work^a

3

Literature review, expert’s opinion, existing data

2

Literature review, expert’s opinion, existing research

1

Literature review, qualitative work^a

10

Literature review, existing research

2

Literature review, existing data

1

Qualitative work only

2

Based on existing research

3

Pilot testing

Yes

18

No

1

Not reported

8

Number of attributes

3

1

4

4

5

10

6

6

7 or more

6

Average number of attributes

5 to 6

Attributes covered^e

Procedure attributes

26

Cost attributes

18

Outcome attributes

14

Other

7

Number of levels

2 to 3

13^b

2 to 4

6^c

2 to 5

5^d

3 to 4

2

4 to 6

1

Labelling

Generic

16

Labelled

6

Both

1

Not clearly reported

4

Number of alternatives (not including opt-out option)

1

2

2

20

3

4

4 or more

1

Opt-out option

Yes

15

No

12