Dyslexia link to school failure*insert a great big groan here*
Dyslexia is defined by the British Psychological Society as
when accurate
and fluent word reading and/or spelling develops very incompletely or with
great difficulty..
You therefore cannot diagnose it until the age at which children are expected to be able to read fluently - approx 7 years. Some of the children taking the Key Stage 1 test will be 6 or only just 7 - it's not really valid to diagnose kids not reaching Level 2 at in the Key Stage 1 tests as dyslexic (even allowing for the fact that the standards for reaching Level 2 don't require a particular single word reading age or a particular reading comprehension level) because they are too young.
ie. the description for Level 2C (lowest part of Level 2) is:
Pupils read most of a simple unfamiliar text independently and use different strategies (phonic, grammatical and
contextual) in reading unfamiliar words. They read from word to word, or sign to sign, or symbol to symbol and may need
support to establish meaning. They show understanding of texts, recount the main events or facts with support and
comment on obvious features of the text, e.g. good/bad characters On the other hand, by definition, any child who, at the age of 10-11, doesn't have reading/spelling skills within the average range for their age is
by definition dyslexic. This is a different test from how well they perform in the Key Stage 2 tests that don't test word reading or spelling skills in the way that they need to be tested to show dyslexia (very often children with quite severe dyslexic difficulties perform well in the Key Stage 2 tests due to the access arrangements made - ie. readers, prompters, scribes, extra time and due to the content of what is being tested - ie. comprehension skills, ability to write in a particular style etc.)
If what the researchers are trying to say is: 'kids who fall below the standard expected for their age in the Key Stage tests need additional investigation to see what's going on' then excellent. If they're trying to say 'they're all dyslexic' or 'failing to meet targets in the Key Stage tests = dyslexia' then they're wrong.
Yes, the definition of dyslexia is a very wide one - it includes children with hearing impairments or visual impairments as well as those with very low cognitive abilities. This is because, with some exceptions, the way to remediate the difficulty is the same - use multi-sensory teaching methods (like - Look, Cover, Say, Write Check for learning spellings) in a very structured way, that requires the kids to 'overlearn' ie. learn the same thing more than once. [Exceptions to using this sort of approach would include children with severe learning difficulties - where an approach based on teaching 'whole word recognition' of words useful to that person might be more meaningful to them and more appropriate for them instead of/in conjunction with a structured, multi-sensory programme to teach reading. Another sort-of-exception would be children with severe/profound hearing impairments (a history of glue ear is very common in children with dyslexia - that's not what I'm talking about here) where you cannot use phonics to teach as the children can't hear the differences in the phonemes.]