If you let MS Word check a document’s spelling and grammar, when
it reaches the end of your document, it provides various statistics including
two readability scores so you can avoid the maths.
Readability scores
There are many factors which affect any reader's comprehension of what you
write. Various means of measuring readability have been developed.
These are not 'quality measures' but related to the 'reading age' of the
text. If you want to see who is likely to understand what you are writing, try
one of the indexes below.
Fog Index
UK newspapers employ the Fog Index (FI) when sub-editing pieces for inclusion. To estimate
the FI:
- Select a passage with about a hundred words. Count the word - C.
- Find the
average sentence length (ASL) by dividing the number of words in the passage by the number of
sentences - S . ASL=C/S
- Count the affixes - A. (An
affix is a word-part which changes the meaning of the base word. An affix
added on the front is called a prefix. An affix then changes the meaning of
the base word. (Look for; a- re- de- co- pre- dis- il- mal- sub- in- im- un-
ir- anti- counter- bi- tri- quad- dec- centi- mili- sub- trans- super- multi-
micro- maxi-) The word can be a noun or verb. When appended to the base word,
it is a suffix. ( -y -al -ic -ee -er -man -ian - ant -ist - ish -ity -ior -ent
-ation -able - full -ness -less -ment etc)
- Count the names and personal pronouns -
P.
-
Subtract the number of personal references from the number of affixes -
(A-P).
Then feed the numbers into the equation:
FI=ASL+(A-P)/ASL
Average Sentence Length plus (Affixes minus
Personal pronouns) divided by Average Sentence Length
The scale:
 | <20 Easy |
| >36 is fairly difficult and |
| Above 50 is unreadable! |
Gunning Fog Index
The Gunning Fog Index formula gives short sentences written in simple
English achieve a better score than long sentences written in complicated
language
It is a modification of the Fog index counts the number of ‘hard words’,
rather than the more complicated affixes. Select a
sample and work out the average sentence length. Now count the words with three
or more syllables but exclude:
| Jargon |
| 'Easy words' like ‘motorcar’, ‘computer’ |
| Three syllable verb forms ending in 'es', 'ing', or 'ed': Not
Sentenced(3) but educated(4) |
| Proper nouns |
(ASL + HW) X 0.4
(Average Sentence Length plus Hard Words) multiply by .4
The average person reads at level 9. Easy reading range is 6-10 and
anything above 15 is getting difficult.
You can avoid the maths involved in working out the index. If you let MS Word check a document’s spelling and grammar, it can
work our some readability scores.
MS
Word compiles the Average number of Syllables per Word (ASW) and average sentence length
(ASL) which it uses to calculate readability ratings.
Flesch Reading Ease score
| The formula for the Flesch Reading Ease score is: |
206.835 – (1.015 x ASL)
– (84.6 x ASW)
| This rates text on a 100-point scale; the higher the score, the easier it
is to understand the document with 60 to 70 being an acceptable score for
literate adults.
|
Flesch-Kincaid Grade Level score
| The formula for the Flesch-Kincaid Grade Level score is: |
(.39 x ASL) +
(11.8 x ASW) – 15.59
| It is designed for US school level. So a score of 8.0 (13ish) means that an
eighth grader can understand the document.
|
Reference:
The Technique of Clear Writing - Gunning (out of print but most
college libraries should stock it).
Back to Getting ready
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