[indrax]

I just signed up to prolific. Their onboarding tutorial/example survey references prescreening and eligibility. I'm guessing it was on researchers to filter the demographics to what was relevant to their study.

I think this is actually the right approach. Some 'balancing' algorithm would have to make assumptions about what's normal, then then the excluded participants wouldn't even show up in the research data.

[psb31]

I think yes, since that’s what it roughly did normally if you didn’t balance. This was a change in the normal behaviour, so if you ran a study from one week the next you wouldn’t have known that your data would change dramatically without additional screening.