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

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

Aspect	Specification	Number of studies (%)
Methods to identify attributes^a	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)
Choice structure	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)

^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)

ISSN: 1471-2334