Sorry for the slow response on this! I asked some folks who work on the Standards and will get you a response as soon as I can.
Hi David~The Standards have been developed using a process that supports internal validity by pulling on the collective knowledge of experts in K-12 education, educational technology, and other fields. The standards are also informed by an extensive public review process, as well as multi-year implementation periods where ISTE collects some data about how they're being used and what impact they have on education.
With this said, the standards development processes do not include formal literature reviews exploring peer-reviewed scholarship about topics like "digital age skills." Additionally, the standards are rarely used in research, although this 2015 article by Bielefeldt documents findings from years of classroom observations using a standards-based instrument.
Currently, ISTE is pursuing two research projects related to the standards: one makes an argument about which technology-related factors matter most for predicting the exhibition of the standards in classrooms, and a second explores the implications of the implementation cycles of the standards as they relate to construct validity.
I hope that's a little helpful!All the best,Brandon