Hello!
I am a researcher within the social sciences for about 5 years, and in the hard sciences for about a year now.
With respect to validation, this falls within the design aspects of a study for me and I have quite some experience in the area, at least four years now as an expert,
Roughly speaking, it is checking a variety of ways various aspects ('items') coalesce together in both a consistent (reliable) matter as well as in the way it was originally designed to measure stuff (validity).
I can definitely both conduct any validity and reliability measurements as well as explain this in easy to understand language :)
Regards,
Sakib