ILIAD data - cleaned

A secondary data analysis was conducted to using data from the Independent Lexical Instruction and Development (ILIAD) project, a supplementary vocabulary program that taught 377 sophisticated vocabulary words across three years to 350 first, second, and third grade students (Goldstein et al., 2017). Two outcome measures were used to assess word learning, a decontextualized definition task and an expressive labeling task. A word was considered learned when children defined and/or labeled vocabulary targets, respectively. The target vocabulary words were characterized for analysis based on available database estimates of their individual word frequency, age of acquisition, phonotactic probability, neighborhood density, and level of concreteness. First, we compare how well the models fit the data using the full ILIAD dataset (first, second, and third, grades combined). While we want to highlight the differences in modeling techniques for each individual grade level, it would be exhaustive. We randomly selected data from first grade to illustrate the unique differences between MARS, multiple regression, and stepwise regression. This data contains lexical characteristics and decontextualized and expressive learning outcomes for 143 vocabulary words.