2008 Test Scores and GPA Distributions

ACT and SAT Scores have reasonable correlation

Weighted GPA has little correlation to standardized test scores

More than half of the applicants have a GPA of 4.0 or better

Many applicants with 4.0 or greater GPA score below the 50th percentile on standardized tests

Because of the large variability in grading and courses offered or taken, weighted 
GPA is not a useful comparison measure. Standardized tests level the playing field

See one reason why standardized test scores matter.