It is important to note that the IAWL is not a single skill measure or mastery measure being used for progress monitoring as criticized by L.
This study evaluated whether the IAWL and ORF measures differentially predicted growth in reading skills.
All participants were assessed six times throughout the study with the IAWL and ORF measures.
The IAWL consisted of one word list that was used in each of the six assessment waves.
To reflect this difference in the potential of each lesson, one word (string) was added to the IAWL from lesson 31, whereas 4 words (shiny, horizon, isolated, silent) were added from lesson 49 to the IAWL.
At each assessment wave, a research assistant presented the student with the 50-word IAWL broken into lists of 10 words printed on cardstock.
Two separate models were run, with IAWL and ORF as the outcome measures.
The ORF and IAWL initial status and slope parameters were then entered in multiple regression analysis to determine the unique variance explained (expressed as [R.
The hierarchical coding scheme used to determine the rank ordering of words on the IAWL was evaluated using a one-parameter model based on item response theory (IRT; Bock, 1997; Embretson, 1996; Embretson & Reise, 2000).