Marin brings her two-year-old son in for a research study on…
Marin brings her two-year-old son in for a research study on how children from ages 2 to 5 develop an understanding of numbers. She is told that her child will either be assigned to an experimental or control group and that she will need to bring him back to the lab every six months for the next two years. In which type of study is Marin’s son participating?