Table 2.

Results of the Delphi study per item (second and third round) with a median score ≥ 6 (full list of results including items with lower scores can be found in the Multimedia Appendix)

Questionnaire Item	Second Round			Third Round
	No.	Median†	IQD	No.	Median†	IQD
I. How important do you think each of the following factors are in determining whether a person will make a first visit to an Internet-delivered behavior change intervention?
A. Whether the potential visitor
- has sufficient skills to use the Internet	89	6	1.5	59	6	1
- has experience with using the Internet	88	6	1	–*	–	–
- is motivated to visit a behavior change intervention provided through the Internet	88	6	1	–	–	–
- perceives the Internet intervention as relevant for himself/herself	84	6	1	–	–	–
B. Whether the Internet intervention
- can be used instantly without downloading special software by the potential visitor	83	6	2	56	6	0
- has a navigation structure that appears to be easy to use at first sight	83	6	2	56	6	0
II. How important do you think each of the following factors are in determining whether a person will stay on an Internet-delivered behavior change intervention long enough to actively engage in and process the educational content provided in the intervention?
A. Whether the visitor
- knows in advance how long it will take to go through the whole intervention	80	6	2	56	6	1
- wants to improve his/her behavior in relation to the topic of the Internet intervention	80	6	1	–	–	–
- perceives the topic and content of the entire Internet intervention as being personally relevant	79	6	2	56	6	0
- experiences the use of the Internet intervention as rewarding	80	6	1	–	–	–
- likes receiving (tailored) feedback on the answers he/she provided on questions	80	6	2	56	6	1
C. Whether the Internet intervention
- displays personal progress through the program (eg, progress bar, page numbers)	78	6	1	–	–	–
- provides the opportunity for a visitor to stop at any moment and to proceed at a later time	79	6	1	–	–	–
- has an aim that is clear to the visitor	79	6	1	–	–	–
- provides information that appears reliable to the visitor	78	6	1	–	–	–
- provides information that is easy to understand for the visitor	79	6	1	–	–	–
- provides information that is perceived to be useful for the visitor to help him/her in changing behavior	77	6	2	56	6	0
- has a tone of voice that is appealing to the visitor	78	6	1	–	–	–
- has an easy-to-follow navigation structure	78	6	2	56	6	0
- provides tailored feedback	77	6	1	–	–	–
- provides tailored feedback which is perceived as relevant to the visitor	77	6	1	–	–	–
- provides behavior change information that seems achievable to the visitor	77	6	2	56	6	0
- can be used free of charge	77	6	2	55	6	0
III. How important do you think each of the following factors are in determining whether a person will revisit an Internet-delivered behavior change intervention?
A. Whether the visitor
- receives a reminder to revisit the Internet intervention	76	6	1	–	–	–
- is committed to revisiting the Internet intervention	76	6	1	–	–	–
- wants to improve his/her behavior in relation to the topic of the Internet intervention	76	6	1	–	–	–
- had a positive experience with the previous visit to the Internet intervention	76	6	1	–	–	–
B. Whether the Internet intervention
- provides new content on a regular basis	76	6	1	–	–	–
- provides the possibility for a visitor to monitor his/her progress in changing behavior	76	6	1	–	–	–
- has previously been experienced as easy to use by the visitor	76	6	1	–	–	–
- has previously been experienced as rewarding by the visitor	76	6	1	–	–	–
- has previously been experienced as enjoyable by the visitor	76	6	1	–	–	–

^*Dashes indicate that consensus was obtained on the item in the second round and, for that reason, was excluded from the third-round questionnaire.

^†All items were scored 1-7 on a 7-point Likert scale.