Specifically, from CogAt's own interpretation website, under "E" profiles:
When students obtain an E profile, it is important to double-check the integrity of their scores. The section "For Additional Information" (below) directs teachers to parts of the CogAT Interpretive Guide for Teachers and Counselors that explain how to check (1) whether the students attempted most of the test items, (2) whether their score reports contain score warnings, and (3) whether the confidence intervals on their plot of scores (shown on the List of Student Scores and the Profile Narrative Report) are reaso[i]nable.[/i]
This would seem to give you a great starting place to discuss the validity of those scores. HTH!
