Dale and Chall developed a formula for the readability of text.
Text examined: 100 word samples (suggested being taken from every 10th page)
Parameters:
(1) number of sentences in selection
(2) number of words not in the list of 3,000 simple words
average sentence length in words =
= (100 words in text sample) / (number of sentences in text sample)
percent of difficult words =
= (number of words not in word list) / 100 * 100%
score =
= 3.6365 + (0.046 * (average sentence length)) + (0.1579 * (percent difficult words))
Interpretation:
• minimum score: around 3.7
• maximum score: around 20
• The higher the score the higher the required grade level.
Score |
Grade |
<= 4.9 |
<= 4 |
5.0 - 5.9 |
5 or 6 |
6.0 - 6.9 |
7 or 8 |
7.0 - 7.9 |
9 or 10 |
8.0 - 8.9 |
11 or 12 (high school) |
9.0 - 9.9 |
college |
>= 10 |
college graduate and above |
ICD-10: ,