Selecting samples or groups of people to study is one of the first tasks in designing your study, and the first ethics question you face in sampling is who you include, or exclude.
Your research ethics application should be clear about why the people you want to study need to be involved, and should possibly include some reflection about who is left out of your study.
Your sample will often determine which ethics committee you need to go to, and who you need to seek permission from, so it is critically important to think through the ethical implications of the sampling strategy you develop.
If your sample includes particular groups in the population – such as children and young people, or vulnerable adults – you will have additional requirements and considerations to address. See our key questions for an overview of the permission and approval you need for research with different groups.