My DS6 recently took the WJ III. I don't understand how the Broad scores are calculated. I researched this forum for answers, but I can't see any of Dottie's posts where she answers this question! Can someone else please explain?
Here are his scores:

Calculations 12 137 >99
Math fluency 34 127 99
Applied problems 30 136 >99
BROAD Math 139 >99

Spelling 31 141 >99
Writing Fl. 10 129 97
Writing sample 12-A 128 97
BROAD Written 139 >99

Letter-Word ID 50 144 >99
Reading Fluency 35 133 99
Passage Comp. 33 145 >99
BROAD Reading 137 >99

Total Achievement 141 >99

I don't understand how his Broad Reading is the lowest Broad score when his two highest individual scores are in the reading group. I would think his broad reading score would be at least 140. What am I missing? I was really hoping to apply for DYS soon. We have a qualifying FSIQ on the WISC and I was hoping to have achievement scores as well. I've heard the WIAT is better for HG kids because the tests are longer than the WJ III. Should I test him with the WIAT and see how he does or go ahead and apply with a portfolio? His WISC scores were:

VCI 138
Similarities 17
Vocab. 18
Comp. 14

PRI 147
Block 16
Pict. Concepts. 19
Matrix. 18

WMI 132
Digit 14
L-N seq. 17

PSI. 131
Coding 15
Symbol 16

FSIQ 148.
I've left a message for the tester about extended norms and was going to ask about the broad reading score as well. The university he was tested at is closed for spring break, so I figured I could get an answer much faster here! Thanks for your input!