Moreover, we assessed a range of academic skills chosen to reflect a gradient of generalizability to the effects of the different instructional approaches. At the end of the year we individually administered standardized intellectual assessments and tests of reading and spelling. Given these measures and the instructional programs under investigation, it would be expected that the effects of DC would be strongest on measures of PA, next strongest on measures of word reading, and weakest on measures of comprehension and vocabulary. This gradient of generalizability is hypothesized under DC because the instruction targets the development of PA, which enables students to improve decoding skills. Through the development of word-reading skills, children develop the ability to read and understand text.
Vocabulary development occurs through the practice of skilled reading.
EC would be expected to have strongest effects on spelling and word reading, weaker effects on PA, and the weakest effects on comprehension and vocabulary. To the extent that non-random assignment simply placed the best teachers or the brightest of the disadvantaged students in one type of instructional condition, we would not expect instructional effects to follow this gradient of generalizability, but rather to reflect a general superiority of one approach across all measured domains. This general superiority would be expected to be apparent at the beginning of the year, and to be relatively consistent in magnitude across domains, or at least not expected to follow one of the predicted gradients of generalizability. As the reader can readily verify in Foorman, Francis, et al. More importantly, children in all instructional groups with higher phonological processing scores in the beginning of the year demonstrated improvement in word-reading skills across the year.