incremental validity

a type of validity used to determine whether a new measure will increase the predictive ability beyond that provided by an existing measure

incremental validity seeks to answer if the new measure adds much information that might be obtained with simpler, already existing measures

For example:
"we examined the incremental validity of the social cognitive tasks by determining whether they would significantly predict variance above and beyond neurocognitive performance"

Source: Schizophrenia Bulletin doi:10.1093/schbul/sbv056