We write a recruit brief with you, then work through a network of professional recruiters to find people who match it. You approve the criteria before anyone is contacted.

The harder question is what happens when the people you need are not on a recruiter’s list. We have interviewed teachers in lower-quintile schools and coding clubs, nurses in clinics in Delft and Nyanga, Grade R teachers in Mpumalanga, and queer youth in South Africa and Zimbabwe who had good reasons not to want to be found.

That work is less about databases and more about trust. It usually means going through an organisation the community already trusts, being honest about what taking part involves, and designing sessions so nobody is put at risk by participating. On one study, some participants were worried about evidence of the research sitting on their phones. That changes how you record, where you meet, and sometimes whether you proceed at all.

We would rather tell you a group is difficult to reach responsibly than promise a sample we cannot recruit safely.