As a dyslexia specialist and assessor, I often get asked what the difference is between a diagnostic assessment and a screening for dyslexia. Both screening and assessment have their value but have distinct differences, so it is important to consider the options and make the right choice to find the answer you are looking for.
There is no blood test or simple, unequivocal or definitive way of determining whether someone is dyslexic or not. Dyslexia is not a medical condition, so ‘diagnosis’ is not strictly to correct word to use. Synonyms such as ‘identification’ or ‘recognition’ might be more useful. However over time the term ‘diagnostic assessment’ has been used in the UK to indicate a set of tests that can allow specialists to conclude that someone is dyslexic.
When deciding to opt for a screening or an assessment, take note of how the terminology can become blurred. The term ‘assessment’ is sometimes used loosely to mean an informal screening, at other times it may refer more accurately to much more extensive testing used in a diagnosis of dyslexia. Assessment and screening are different psychometric processes that vary in the time taken to carry them out and in their cost.
Psychometrics (or psychometry) is a branch of psychology dealing with the design,
The characteristics of screening
On the whole dyslexia screenings are designed to be a simple, relatively quick (often around 45 minutes) and cost effective method to categorise people into groups who are ‘at risk’ of dyslexia with reasonable accuracy.
Screenings use tests designed to reveal a person’s attainment, such as reading and spelling, as well as their ability, for instance in problem solving. While diagnosis is not the main aim of the screening, they may still include tests that are diagnostic in character. For instance some online screening tools analyse aspects of learning like the speed at which a person can process simple visual information and how well they can identify individual sounds within words (known as phonological awareness).
The accuracy of a screening tool varies and there may be ‘false positives’ or ‘false negatives’. ‘False positives’ are those who are predicted by the screening tool to be dyslexic when they are not and ‘false negatives’ are those who are found not to be dyslexic by the screening when in fact they are.
An example of a ‘false negative’ where a dyslexic person may be missed by the screening test, may come from a ‘well-compensated’ person with a less severe version of dyslexia – the screening test may not be subtle enough to pick up their difficulties.
As there will always be cases where correct classification cannot be certain, it means that screening shouldn’t be seen as an alternative for thorough and wide-ranging assessment. Screening tools are best used as a basis for indicating the likely need for further testing or whether specific programmes of action might be helpful to an individual.
After the screening
A short report is issued which gives the likelihood of dyslexia. This often ranges from ‘no signs’ and ‘some signs’ of dyslexia, through to ‘mild’, ‘moderate’ and then ‘severe’ dyslexia. The report is likely to suggest that the profile produced from the results ‘are typical of someone who is…’ rather than making a definite statement. The report should also make recommendations for action to take that may include diagnostic assessment and/or types of teaching and accommodations that should be considered to support the person in their education or work.
Characteristics of diagnostic assessments
Assessment is a much more extensive and multifaceted process by which a diagnosis of dyslexia may be achieved. A battery of different diagnostic tests are used over a number of hours and the tests are administered and results interpreted through the judgement of an experienced and appropriately qualified specialist such as a Chartered Psychologist, an Educational Psychologist or a specialist Teacher/Assessor.
What is important to recognise is that it is the interpretation of the assessor that diagnoses the person and not the tests in themselves. The results allow the professional to come to a conclusion about a person’s strengths and weaknesses across the bank of tests and that conclusion does not rely on any individual test for a diagnosis.
The tests assess difficulties in 3 key areas:
1. Skills in literacy and numeracy (spelling, writing, reading and arithmetic). These tests will help to establish the degree of difficulty a person has in such areas, faulty strategies and skill-gaps.
2. Language, working memory and processing skills known to be associated with dyslexia. These tests focus on identifying the most typical blocks or barriers to learning.
3. General language and cognitive skills (visual problem solving, verbal reasoning and vocabulary) The data from these tests is important because they can reveal if there is a big gap between a person’s ability to explain things in writing and verbally.
Assessors are looking for a pattern of results from the tests from which they can draw conclusions and they may choose to use additional tests if extra evidence is required to make that conclusion. Such a pattern usually shows a marked variation of proficiency across the test-taker’s skills. When compared to the ‘norm’ the dyslexic person’s profile of results will highlight areas of strength and weakness which may not be similar to their peer group at the same stage/age.
After the assessment
Usually the diagnostic assessment is followed up by the preparation of a detailed written report which gives the conclusion of the specialist with regards to the person’s strengths and weaknesses and their conclusion regarding their dyslexic status, a summary of the test findings and a detailed set of recommendations for the types of support thought appropriate for the individual in their education or work. You should be given the opportunity to ask questions about the conclusions reached and to make sure that you have a full understanding of the contents of the report.
So what is your answer, assessment or screening?
The process you choose depends on the reason you are seeking an answer. It may be that you are keen to know if you are dyslexic or not, or it might be that you are looking for support in an education or work setting. Dyslexia is considered a disability under the Equality Act 2010, making reasonable adjustment an appropriate action to take. It may be that you are curious about some difficulties you are having or want information that can be passed on so you can get better support from them. Take your time to make your choice and find out what, you, your educational establishment, or employer requires. I hope this blog has helped you to understand the main differences. Good luck with your search for an answer.
Jan Halfpenny is a dyselxia specialist and assessor. She delivers training, workplace needs assessments and tuition for adults in the workplace. She is dyslexic herself and has a wealth of experience of dyslexia and reasonble adjustments
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