Ayrer, J. E., & McNamara, T. C. (1973). Survey testing on an out-of-level basis . Journal of Educational Measurement , 10 (2), 79–84. https://doi.org/10.1111/j.1745-3984.1973.tb00785.x

Test data (mean grade equivalent scores) from one school district in Philadelphia were compared over three years.

17,000 pupils 3-8 grade in a Philadelphia school district.

Scores on the Reading Comprehension subtests of the Iowa Test of Basic Skills.

Mean (district level) grade equivalent scores declined over three years of test data, corresponding with an increase in the number of students taking out-of-level tests.