Table 1. Semi-Structured Interview Template.

1. What kind of recruitment strategies have you used where technology has been involved?    (a) What kinds of technologies have you used in research recruitment?    (b) Is there one technological method(s) you’d recommend over another?

2.Why was it decided to use technology to recruit?

3. Was there anything about using this technology that you found advantageous or facilitated recruitment?

4. Was there anything about using this technology that you found impeded recruitment?

5. Were you able to achieve the sample required?    (a) If not, have you ever worked on study without technological support in recruitment where the required sample was achieved? (a.1) Why do you think that is?    (b) Do you think using a recruitment strategy without this technology would have yielded a similarly sized sample?

6. What was your retention rate like for this RCT?    (a) Do you think your recruitment approach impacted retention?

7. Can you describe the cohort you were seeking to recruit with regard to their age group, sex and educational or socioeconomic status?    (a) Do you think that the type of cohort you were recruiting (e.g. with respect to age, gender, ethnicity, socioeconomic status had an impact on your recruitment process)?

8. Did the use of technology cost anything above and beyond that of not using it with respect to resources?    (a) Do you think it was worth these costs?

9. Has COVID impacted the way in which you think about recruiting for RCTs?

10. How might technology be used to improve recruitment for randomised controlled trials in the future?    (a) What do you think of the real-world implications of such recommendations (e.g. with respect to feasibility, accessibility and appropriateness).

11. Do you think there are any other potential barriers to using technology for recruitment that have not yet been discussed?

12. Do you think there are any other potential factors that can enable recruitment that have not yet been discussed?    (a) Any final thoughts/comments