Dosage in Reading Interventions – Examining the Predictive Power of Different Dosage Measures on Students’ Reading Fluency, Motivation, and Self-Concept

A reading intervention’s effectiveness is influenced by its dosage, but different dosage measures exist. This study examines (a) the relative importance of four different dosage measures in predicting students’ development in reading fluency, motivation, and self-concept, and (b) whether these measures’ predictive power depends on students’ initial reading ability. A total of 227 German primary school students (50.7% female, M = 8.62 years old) participated in an evidence-based reading intervention on reading fluency. Before and after the intervention, we assessed students’ reading fluency, motivation, and self-concept. During the intervention, we documented dosage via four measures (contact time, time period, session frequency, and number of words read). Dominance analyses revealed that the time period showed the highest relative importance in predicting changes in reading fluency and reading motivation, while no dosage measure significantly predicted reading self-concept. Additionally, low-performing readers benefited more from longer time periods compared to higher-performing peers. Our findings highlight the importance of extended time periods in enhancing reading outcomes, especially for low-performing readers.