My son was tested at 4 by a grad student and at 8 by a psychologist who had been testing students for close to 20 years.
His numbers came out to be very similar (of course the first test was the WPPSI and the 2nd was the WISC so there was some difference).
Neither tester had much experience testing children with numbers like his. Neither had much to offer in the way of recommendations because they were not super familiar with EG/PG children. However the numbers were useful in advocating for a grade skip and acceptance into DYS.
Both experiences were good. The grad student, who was younger, was more patient.
Personality and enthusiasm and intellectual curiosity in the tester probably play a big role in the success of the testing and other than going with highly recommended testers (who are pricey), I don't know how you'd filter for that. But to some degree, all those variables must be factored into the actual testing. It's supposed to be objective, not subjective, right?
