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Table 3 Overview of the design of the choice tasks among included studies

From: Vaccine preferences driving vaccine-decision making of different target groups: a systematic review of choice-based experiments

Aspect Specification Number of studies (%)
Methods to identify attributesa Characteristics vaccine, disease 2 (4.8)
Expert consultation 19 (45.2)
Literature review 33 (78.6)
Previous DCE 4 (9.5)
Qualitative research 28 (66.7)
Theories vaccine decision-making 1 (2.4)
Vaccination policy 1 (2.4)
Not reported 1 (2.4)
Choice structure Binary 3 (7.1)
Multinomial 39 (92.9)
Methods to create choice sets, of multinomial studies (n = 39)a D-efficiency 3 (7.7)
D-efficiency using software 11 (28.2)
Fold-over 3 (7.7)
Random 3 (7.7)
Random using software 1 (2.6)
Other software 5 (12.8)
Not reported 13 (33.3)
Format of choice question, of multinomial studies (n = 39)b Forced choice 4 (10.3)
Forced choice, followed by opt-out 12 (30.8)
Unforced choice with opt-out 18 (46.2)
Unforced choice with opt-out, followed by forced choice 2 (5.1)
Unclear 3 (7.7)
Number of choice tasks < 10 17 (40.5)
10–15 10 (23.8)
> 15 10 (23.8)
Not reported 5 (11.9)
  1. aAs multiple methods could be used to identify attributes, the total number of studies exceeds the total amount of included studies (and 100%); bNote the proportion (%) is calculated from studies applying multinomial choice structures (n = 39), not from the total amount of studies (n = 42)