Imagine you have two toys, a teddy bear and a doll, and you want to know which one is better to play with. This is like what scientists do when they study different ways to treat illnesses. They want to know which treatment is better.
Comparative effectiveness research is when scientists compare different treatments for the same illness to find out which one is best. They might look at how well the treatment works, how much it costs, and if it has any side effects.
It is like when you ask your friends if they like the teddy bear or the doll better. The scientists ask lots of people who have the same illness which treatment they like best.
The scientists then use all the information they gather to help doctors and patients make better choices about which treatments to use. It is like helping your friends make a better decision about which toy to play with.