Created by CE 4/3/20, thanks to Doris Coveny for the final question to trigger this.
The CORE-OM and the derivative short forms were designed for use with adults, i.e., and rather loosely, from age 18. The papers about the YP-CORE (to date) describe as for ages 11 to 16 which seems to leave 17 year olds in a limbo.
I recommend that you use the YP-CORE up to age 17 and the adult measures from age 18 on. If you have clients/participants who might pass through whatever change age you’ve chosen change age you have chosen then obviously things are more complicated. That doesn’t really fit in an FAQ answer so I have created a small background document that discusses that issue and some other issues relating to age. However you can probably ignore that if your clients/participants are all older than 18 and younger than 65.