Expert answer
Our work with other researchers, especially Robin Morris and Jack Fletcher, on examining subtypes of reading problems has demonstrated that a phonological weakness is present in 90% of all struggling readers. Phonological problems may be associated with problems in other areas such as memory as well. A small group of children may demonstrate problems in rate alone and not in phonology. These results are for young children; we are now working on an adolescent study to see if the same is true for this group of older children.