I dont know about the ITBS test and Renzulli scales. But since my DD took the CoGAT, i read about it extensively. This link here is very informative.You might want to jump to page 18 if you just want to read the interpretations.

www.riversidepublishing.com/products/cogAt/pdf/cogATshort.pdf

There is some more concise information here:

www.lincoln.edu.ar/es_counseling/testing/Interpreting%20CogAT%20Test%20Scores%20Abbr.doc