Procedural differences in the calculation of the prevalence of reading difficulties in Spanish-speaking school children / Diferencias procedimentales en el cálculo de la prevalencia del retraso lector en escolares hispanoparlantes

Abstract The prevalence of reading difficulties (RD) reflects controversial data ranging from 3.1–3.2% to 17.5%. Possible explanations are partly based on the incidence of orthography-specific factors influencing the reading process, but also on methodological differences that hinder comparison of the reported results. For this reason, the present study aims to analyse the prevalence of RD in a sample of 1,408 Spanish-speaking school children by comparing different ways of calculating the prevalence rate. The results reflect a prevalence of 2.2−5.3%, consistent with data reported for predominantly transparent orthographies. Some of the procedures used to identify RD are more accurate in early school years than at more advanced moments of schooling. Furthermore, the consideration of students’ sex when calculating the prevalence of RD seems to represent a more sensitive way of identifying students with RD.