Psychologia 15(3), 267–289, 2008

In the Greek language, timed measures of reading are considered to be of primary importance for reading assessment and evaluation of reading difficulties. In the present study we compared schoolchildren with dyslexic profiles or diagnosis to the general Greek school population. Effect size analyses confirmed the importance of reading speed measures both in primary (307 children from Grades 3 and 4) and secondary (213 Grade 7 children) education in distinguishing between the two groups. Effect sizes were comparable whether reading rate was assessed with a raw time measure (total time to read aloud the material) or with a derived fluency measure (time per correctly read item; word or nonword), especially for the older children and particularly in the case of reading connected text. We analyzed the results further using exploratory factor analyses. Using raw reading time measures, reading speed made up a distinct dimension of performance, orthogonal to the (reading and spelling) accuracy and general cognitive ability components. However, when fluency as time-per-item was used, the corresponding measures varied largely along the same dimensions as reading and spelling accuracy, failing to form a clear time-related dimension, and resulting in a poorly interpretable structure. In both cases, rapid automatized naming (RAN) measures correlated with both reading dimensions and not selectively with fluency. The results of these analyses support the contention of primary importance for timed measures of reading performance in the assessment and diagnosis of reading difficulties.