Thanks for all your input! My powers of Google rarely fail me, but it is proving nearly impossible to determine exactly how broad scores are calculated.
Some of it is propietary/confidential information, but one can glean certain parts of it. (I'm pretty sure it's age-normed mot grade-normed.)
Everyone who has a WJ-III (ach) report, check out the "W" column, if your report has one.
It appears that the W's for the "BROAD" and "BRIEF" and othe combinations are indeed simply the (unweighted) arithmetic mean, i.e. the "average" or the W's for the component tests.
Can others of you check to see if you can confirm this pattern.
We don't know how to get W's from raw scores (and age) but that's not really important.
What's a more important unknown for this discussion is how W is translated to SS (Standard Score(?)). It's probably a linear function (with rounding), but it could be a different linear function for each test (and hence for the combinations of tests like "BROAD" and "BRIEF"). One could try to deduce the coefficient from various examples of score combinations.
