contrary: the whole point of identifying risk factors is to alert parents, physicians, and teachers to potential obstacles children might face so that effective interventions can be devised and implemented.
In the absence of other (noncorrelational) evidence, therefore, these predictors cannot be considered causes of reading problems but rather as associated conditions implicated in reading difficulty. Nevertheless, the fact that these characteristics correlate with subsequent reading achievement is potentially very useful for identifying children who may be in the greatest need of intervention. Our goal in this chapter is to present ways of identifying who should receive services to prevent reading difficulties.
That an individual or group has been identified as being at risk for reading difficulties has no direct implications for the nature of the appropriate intervention. It is not the case that treating the predictor itself is necessarily the right approach; for instance, if difficulty with letter identification turns out to be a predictor, this does not mean that instruction on letter identification is a sufficient or the best treatment for preventing all reading difficulties (see Adams, 1990). Conversely, the skills that are the focus of treatment may not necessarily be the ones on which the identification of the individual or target group was based. In practice, identification criteria and treatment plans can, and often will, be chosen somewhat independently of each other.
It should be borne in mind while reading this chapter that relationships between effective predictors and reading difficulties are markers only and that other mediating variables, which are not measured in a particular research study, may also correlate with reading difficulties. Again consider letter identification: Scanlon and Vellutino (1996) found a moderately high correlation (r= .56) between letter identification and reading achievement. In this same study, the correlation between number identification and reading achievement was .59. Since these results indicate that both poor letter identification and poor number identification predict reading difficulty, they weaken or at least complicate the hypothesis that either of them is a direct cause of reading difficulty. Both may be marker variables for another factor that goes further to explain both letter and number identification.