Understanding variation in prospective poor decoders: A person-centred approach from kindergarten to Grade 2.

In the present study, we aimed to clarify variation in prospective poor decoders by studying the development of their word decoding skills during the first 1½ years of formal reading education and their unique pre-reading profiles before the onset of formal reading education. Using structural equation modelling and a factorial mixed model analysis of variance (ANOVA), we found autoregression and growth in the word decoding efficiency of prospective poor decoders (n = 90) and matched prospective adequate decoders (n = 90) in first and second grade. However, the gap between the two groups widened over time. Next, we zoomed in on the group of poor decoders by retrospectively studying their individual variation regarding cognitive and linguistic pre-reading skills. Using latent profile analysis, we found three distinct pre-reading profiles: (1) Poor PA, Letter Knowledge, RAN, and Verbal STM; (2) Poor PA and Letter Knowledge; and (3) Poor RAN. Together, these findings suggest that reading difficulties emerge at the intersection of multiple risk factors which can be detected in kindergarten, and that these reading problems persist throughout early reading education.