QUICK ESTIMATES OF THE RELATIVE EFFICIENCY OF TWO TESTS AS A FUNCTION OF ABILITY LEVEL
Frederic M. Lord · Journal of Educational Measurement · 1974
When comparing two tests that measure the same trait, an overall comparison is not enough. Separate comparisons should be made at different levels of the trait. A simple, practical, approximate formula is given for doing this. The adequacy of the approximation is illustrated using data comparing seven nationally known sixth‐grade reading tests.