Background on Empirical Validation of Text Complexity

Without some form of brain imaging, the best way to determine the complexity of a text is by imposing a
response requirement on a reader to check for understanding. It is important that item writing protocols
focus on the complexity of the text itself avoiding pitfalls in item writing that add easiness or hardness to
the understanding of the text.

Early in the development of the Lexile Framework for Reading, researchers evaluated the predictability of
reading items and determined which item type was best suitable for predicting a text’s complexity. The
embedded sentence completion item, often called Lexile native items, won the day. Figure 1 shows an
example of a native Lexile item.