The SMOG readability formula is a quick and simple means of determining the readability of written materials such as patient health information booklets or consent forms.
A polysyllabic (which is polysyllabic) word has 3 or more syllables.
Some rules for the SMOG formula:
(1) A long sentence separated by a semicolon should be counted as 2 sentences.
(2) Count a hyphenated words as 1 word.
(3) Include the following as polysyllabic:
(3a) Numbers, if polysyllabic when pronounced
(3b) Proper names, if polysyllabic.
(3c) Abbreviations if the expanded term is polysyllabic.
If the document contains 30 or more sentences:
(1) Select 10 sentences from the beginning, 10 from the middle, and 10 from the end of the document, for a total of 30 sentences.
(2) Count the number of polysyllabic words per sentence.
(3) Calculate the total syllabic word count as
total polysyllabic word count in 30 sentences =
= SUM(polysyllabic word count in all 30 sentences)
If the document contains less than 30 sentences:
(1) Evaluate all of the sentences in the document.
(2) Count the number of polysyllabic words per sentence.
(3) Calculate the total syllabic word count as
adjusted polysyllabic total count =
= SUM(polysyllabic word count in number of sentences) * (30) / (number of sentences present)
|
Total Number of Polysyllabic Words
|
Approximate Grade Level
|
|
1 – 6
|
5
|
|
7 – 12
|
6
|
|
13 – 20
|
7
|
|
21 – 30
|
8
|
|
31 – 42
|
9
|
|
43 – 56
|
10
|
|
57 – 72
|
11
|
|
73 – 90
|
12 (senior high school)
|
|
91 – 110
|
13
|
|
111 – 132
|
14
|
|
133 – 156
|
15
|
|
157 – 182
|
16 (senior college)
|
|
183 – 210
|
17
|
|
211 – 240
|
18
|
|
> 241
|
> 18
|
where:
• The actual grade level is a range from the approximate grade level + 1.5 grades.
According to Contreras et al the SMOG level for text with 30 or fewer sentences:
SMOG grade reading level =
= 3.1291 + (1.043 * SQRT((number of polysyllabic words) + (((30 - (number of sentences)) * (number of polysyllabic words) / (number of sentences)))))
Interpretation:
• If the approximate grade level exceeds that of the target population, then it is necessary to reduce the number of polysyllabic words by "dumbing down" the words.
