Recently my son (10 years) was tested on both the Woodcock Johnson and WIAT achievement tests. The math scores from test to test were significantly different.

My question is:

What are the possible explanations for the differences in the two test results? How often do differences like this occur?

WIAT III

Numerical Operations 105
Math Problem Solving 123
Math Fluency Addition 114
Math Fluency Subtraction 117

Mathematics 115
Math Fluency 113


Woodcock Johnson III (5 weeks later)

Calculation 130
Math Fluency 121
Applied Problems 127

Broad Math 131
Math Calculation Skills 130


Thank you all

I have not adminstered these tests myself, but I have seen a number of evaluation reports that includes these tests. From my perspective, the WJ almost always yields a higher score than the WIAT. From what test administers have told me, the WJ generally has test items that are shorter and less dense. For my clients (generally students with disabilities), they can score quite well on the WJ because their LD's do not create as much of a drag than they would on more complex, longer test items.

I would ask the person that gave the test to give you an example of test items for each test. I would also ask if any of the tests had time constraints or not.

From my experience - and again I do not deal with a random cross sample of kids, but rather a very specific profile, I see this ALL the time. And I see this same pattern for the writing and reading sub tests too.