I conducted a series of surveys in November 2020, and in total I had about 435 respondents. Now I would like to conduct a follow-up survey where I would like to reach the same respondents with additional questions. However, after I set the screening criteria to reach the respondents who already participated in the 2020 studies, I get a message that there are only less than 25 respondents available.
Is this common? What is the percentage of participants who drop out over time? How long do they typically stay active on Prolific?
only <25 out of 435 seems very low to me even when 18 months have past since you conducted the original studies. Maybe there are some technical issues related to screening users that participated in your initial studies. In my own follow-up studies, I used the “Custom Allowlist” feature and entered the IDs there. It worked very well. If I remember correctly, there were a couple of drop-outs but those that were still available to do the follow up were about 90% of the original studies sample size. Here are some details about the follow-up studies that I have done on Prolific:
First wave: January 2021
Second wave: January 2022
Sample size was 1000 UK citizens
For the second wave >90% were eligible and from those we received more than 700 responses in the second wave, which I consider a very high response rate.
First wave: January 2022
Second wave: March 2022
Sample size was 1000 US citizens
For the second wave >90% were eligible and from those we received more than 750 responses in the second wave, which I consider a very high response rate.
Another reason for your low eligibility number could also be that your initial study had a very niche subgroup as target population, which drops out more likely for whatever reason (e.g. COVID or other health reasons)?
Hope that helps.