RocketReader Reading Levels - FAQ
Q. What are the Benefits of Reading Level?
Reading level helps to answer the following popular questions:
- How hard is a book to read?
- Where may I find graded reading lists?
- What are the hardest books in the collection?
- What are the easiest books in the collection?
- What books would be suitable for my children?
- What Authors should I read that are at my reading level?
Q. What is Reading Level?
The reading level is a way of designating the reading difficulty
level for English text books in a collection. Reading
level is given a rating of 0 through to 100. The hardest book in
the collection has a reading level of 100. The easiest book in
the collection has a reading level of 0.
Q. Who uses the RocketReader Reading Levels
The RocketReader reading levels have been used on the stories within the RocketReader software since 2003.
During 2005 and 2006 they have been ehanced to include more reading factors and to normalize the results against 20,000 English books in the Gutenberg collection.
In 2006 they were added to RocketReader Online.
Q. How is Reading Level Calculated?
The reading level calculation is complex. It takes into account 12
qualities of reading and uses statistics to spread the scores of
books in the collection uniformly between the values 0
Q. How are the Reading Levels distributed?
The reading levels start at zero (easiest) and finish at 100
(hardest). The books in the collection are distributed
uniformily accross this range. For example, one quarter of the
ebooks in the collection exists in the top quartile, ie.
in the range of scores 75 through to 100. As another example, the
books with reading levels zero to 10 represent one tenth of the
Q. What kind of book has the highest reading level?
Currently, according to the RocketReader Reading Level, the most
difficult book measured (reading score of 100) is:
"Note on the Resemblances and Differences in the Structure and the Development of the Brain in Man and Apes"
by Charles Darwin.
Q. What is the easiest book ever measured?
Currently, according to the RocketReader Reading Level, the easiest book measured (with a reading level score of 0) is:
"Mary Oliver: a Life"
by May Sinclair.
"Bunny Rabbit's Diary"
by Mary Frances Blaisdell comes a close second.
Q. What factors make a book hard to read?
The RocketReader Reading Level uses the following determinates
- the prevalance of large words
- the prevalance of short words (-)
- the average number of words in a sentence
- the average number of syllables per word
- the prevalance of digits or numbers
- the prevalance of the most common 1000 words in the English
- the prevalance of compound sentence clauses (sentences
- the average number of words per paragraph
- the difference between the frequency distribution of the
letters in the ebook compared with a "typical" English frequency
- the difference between the frequency distribution of the
first letter of each word compared with a "typical" English
frequency distribution of first letters.
- the number of distinct unique stemmed words divided by the
number of words in the document
- the occurance of profanity - this increases reading level to
ensure that books with profanity are rated higher
Q. Why use these factors?
Some of the factors used to determine the RocketReader Reading
Level have been used in different reading metrics for many years to
classify the reading level of text. However, there are many new
reading factors. It it somewhat subjective what makes a book more
or less difficult to read. A way of checking whether the reading
factors generally agree with each other is to calculate what is
referred to as a cross correlation between the factor values over
the reading corpus, eg the Guterberg collection. This has been
done and there is general agreement (positive correlation) between
the 12 reading factors except one; the prevalance of profanity.
This factor was included simply to ensure that books with profanity
were bumped up in reading level to ensure that children working
through the "easiest to read books" would not accidently stumble
Q. Why Not Use Well Known Reading Levels Such as Fog, Kincaid,
SMOG, ARI or ____ (name popular reading metric)?
Most existing reading levels only use two to four determinates in
calculating a reading score. The RocketReader Reading level uses
twelve. These extra determinates are important especially when
rating books of the lower grade levels. Additionally,
the RocketReader Reading Level has nice statistical properties:
Each factor contributes to the overall score in exactly
the percentage allowed by each factor weighting. Within the
main corpus (20k books in the Gutenberg collection) the scores
are distributed uniformly throughout the numerical range of the
metric (0 to 100).
Q. I disagree with the rating on a specific ebook!
We have found some books contain formatting that throws off the
From time to time we have adjusted the parsing of the reading text
level to cope with these special
cases. However, we acknowledge that there still may be further
special cases to be considered.
Send us an email with the title of the book and the reason you
believe it was misclassified.
You can contact
and the Gutenberg Project here
Q. What languages are rated?
The Reading Level is designed to classify English books. A number
of of the reading level determines are tied to English properties
such as common abbreviations, frequently appearing words, common
suffixes, methods of stemming words, syllablization, punctuation
and frequency distributions of iall letters and the first letter of
For this reason the reading level is only currently provided for
Q. You crazy scientists with your statistics! Why reduce
something as complex as a work of literature down to a single
Simply, because it is useful. When children learn to read, it is
great if they can advance through gradually more
challenging books. This RocketReader Reading level allows readings
to be selected on this basis. It also provides many other uses and
benefits to educators,researchers and adults!
Q. Can I rate my own texts and books?
Yes, you can do this in RocketReader (the software) and RocketReader Online. In RocketReader Online simply click on the "My Docs" button in the top right hand corder of the reading page. Then upload a document. Once the document is uploaded, the reading level will then appear next to that document name.