STATISTICAL COMPARISON OF TWO SERIES OF GRADED READERS.

The article presents information on statistical comparison of two series of graded readers. In the search for a useful method of quantifying the difficulty level of text intended for children, a redundancy measure derived from information theory was considered. Redundancy of letters in written English is a function of the relative frequency of each letter and of the constraints that operate in the language to produce combinations of letters with vastly different frequencies. In view of the stability of these measures with a sample size of six thousand letters, it is of some interest to apply them to a comparison of two series of graded readers. The texts of three levels of two widely used series of basic, readers, Sheldon Basic Reading Series and Ginu Basic Readers, were key-punched on IBM cards, using a 28-character alphabet: the 26 letters of the English alphabet plus word mark and sentence mark. It is apparently possible to design reading texts for a given level of difficulty, since two different series show great similarity in redundancy, growth of sequential constraint, mean word-length, and mean sentence-length at each of three levels.