Diagnostic teaching with all its ramifications is one of the trends in education which has had profound implications for the field of reading. Unfortunately, too much of the emphasis has been on diagnosis and not enough on teaching. Teachers are constantly bombarded with new tests diagnostic, criterion referenced, etc. all of which are reputed to accurately pinpoint the reading needs of all students. Many of the results of these measures are at best tenuous: the fact that a well trained teacher is the best diagnostician is one fact that is often ignored in any implementation of diagnostic teaching.
Cassidy, J. (1978). The Reading Field Agent: A Model for the Diagnostic Teaching of Teachers. Reading Horizons, 18 (2). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol18/iss2/8