I have read through the tests that help to clarify whether or not a child is dyslexic. The battery of tests is extensive. Can you tell me what the "absolute" assessments for dyslexia are?
Dr. Pierson's Response: 
There are no absolute assessments for dyslexia. Rather, the key in diagnosing dyslexia is to find a pattern of strengths and weaknesses, which typically includes strong oral comprehension skills with weak phonological processing, reading, spelling, and/or writing skills. In addition, the child may or may not have word finding issues and/or may or may not have difficulties with verbal expression. He or she may have problems with phonological aspects of spelling versus orthographic challenges. There are many questions to answer and the initial questions/reported problems drive the tests chosen at the start of the assessment. But as the assessment progresses and weaknesses come to light, the tests used to delve further into those areas and make a definitive diagnosis may change. At my private clinical practice, we review each case history (and any other information) prior to the testing and that determines what tests we start with; but then during the assessment, we may add, delete, and/or change tests depending on what we are seeing.

To help guide you, here is a sample of what areas should be assessed and what some "starting" tests might be:
Receptive vocabulary -- Peabody Picture Vocabulary Test - 4

Oral language comprehension and use-- Clinical Evaluation of Language Fundamentals - 5 or the Comprehensive Assessment of Spoken Language

Phonological awareness, phonological memory, and rapid automatic naming -- Comprehensive Test of Phonological Processing - 2

Decoding real and nonsense words -- Test of Word Reading Efficiency - 2

Reading decoding, fluency, and comprehension -- Gray Oral Reading Test -5

Spelling -- Test of Written Spelling - 5

Writing -- Quite honestly, it is my experience, and thus I am of the opinion, that none of the standardized tests is capturing writing difficulties well. That said, tests such as the Test of Written Language - 4 or Writing Process Test can be informative at some level. If word finding/retrieval issues are present/suspected, it can be helpful to compare receptive vocabulary to expressive vocabulary -- the Expressive Vocabulary Test - 2.

It takes approximately 4-6 hours for me to assess a child to make a diagnosis -- the older the child, the longer it takes. I'm not sure the context in which you are working. If it is the schools, I know that the time to do a comprehensive assessment can sometimes be limited/constrained. Regardless, it behooves us to do a comprehensive assessment, one that includes oral language skills because these deficits can be subtle and be missed during evaluation. One’s oral language comprehension is the foundation for learning to make sense of what one reads. Difficulties in verbal expression can be manifested in writing. If there is a weakness in oral language skills it must be addressed in conjunction with reading and writing intervention. Here is the link that discusses what an assessment entails -- http://dyslexiahelp.umich.edu/professionals/learn-about-dyslexia/diagnosing-dyslexia