A recent report from the College Board investigates two key issues: grade inflation, in which teachers over time assign increasingly higher grades for a given level of achievement; and
grade nonequivalence across schools, in which teachers in different schools apply different grading standards for the same curricular material.
The author concludes that such practices as grade inflation and grade
nonequivalence make it difficult for college admissions officers to make a valid assessment of a student's achievement in comparison with other applicants.
Testing for measurement and structural equivalence in large - scale cross-cultural studies: addressing the issue
of nonequivalence.
In adding to his definition the proviso «but a and b are not identical,» he is referring the reader to already established assumptions and definitions which have provided the condition for the possibility of nonidentity and
nonequivalence and have indicated what the differentiating «interesting» relations might be.