Scale scores in New Jersey are set so that the Partially Proficient-Proficient scale score is 200 and the Proficient-Advanced Proficient cut score is 250. 

The reason scale scores are used rather than raw scores is because they control for item difficulty. That is, the if a test is really hard, and a raw score of 15 would be considered Proficient in one year.  But if a test is easier another year, then a raw score of 18 may be considered to be Proficient.

To find the achievement level for a student, his or her raw score is converted to a scale score X and then is: