Readership Research

Readability Research
Simply defined, readability is the sum total
of all the elements and their interactions that
affect the success of a piece of printed material.
Success is measured by the extent to which readers understand the piece, are able
to read it at an optimal speed, and find it interesting
(Dale & Chall, 1948).
Several formulas have been developed to
determine objectively the readability of text.
One of the best known is the Flesch (1948)
reading ease formula, which requires the researcher
to select systematically 100 words
from the text, determine the total number of
syllables in those words (wl), determine the
average number of words per sentence (sl),
and perform the following calculation:
Reading ease 5 206.835 2 0.846wl 2 1.015sl
The score is compared to a chart that
provides a description of style (such as “very
easy”) or a school grade level for the potential
audience. An alternate version of the Flesch
formula is the Flesch–Kincaid Readability
Test that uses a score of 0–100. This number
is translated to a corresponding school reading
level. For example, the Flesch–Kincaid
grade level for this chapter is calculated as
twelfth grade.
Another measure of readability is the Fog
Index, which was developed by Gunning
(1952). To compute the Fog Index, researchers
must systematically select samples of
100 words each, determine the mean sentence
length by dividing the number of words
by the number of sentences, count the number
of words with three or more syllables,
add the mean sentence length to the number
of words with three or more syllables, and
multiply this sum by 0.4. Like the Flesch
index, the Gunning formula suggests the
educational level required for understanding
a text. The chief advantages of the Fog Index
are that the syllable count and the overall
calculations are simpler to perform. (Check
the Internet for online calculation programs
to compute the Fog Index.)