G. Spache devised the Spache Readability Formula
in 1953 through an article, A New Readability Formula for Primary-Grade Reading Materials
, published in The Elementary School Journal
. The formula calculates the grade level of a text sample based on sentence length and number of unfamiliar words. The Spache Formula considers unfamiliar words as words that 3rd grade and below do not recognize. The Spache Formula is best used to calculate the difficulty of text that falls at the 3rd grade level or below.
Spache Readability Formula is similar to the Dale-Chall Readability Formula. While Spache was designed to access the readability of primary texts through the end of third grade, The Dale-Chall is ideal to gauge the readability of more advanced texts -i.e., fourth grade and above. Which formula should you use, and when? 1.
If your text sample is equivalent to a third grade text or below, use the Spache. 2.
If your text sample is more advanced than third grade, use the Dale-Chall.
If you are not sure about the level of difficulty of the passage, first use the Spache formula. If the Spache readability results are higher than third grade, run the same passage again with the Dale-Chall.