AS OF MAY 2016, THIS PLUGIN IS NOT BEING MAINTAINED AND WILL NOT RECEIVE ANY FUTURE UPDATES. 
CONTACT ME IF YOU’D LIKE TO LIST AN ALTERNATIVE HERE.
Shows word and sentence counts plus a readability analysis of the post 
currently being edited using three different readability measurements.
Readability analysis is an attempt to show how difficult a text is to read. 
There are several methods of doing readability analysis. The most popular 
methods are used here. The Flesch and Flesch-Kincaid methods use formulas based 
on the average number of words per sentence and the average number of syllables 
per word. The Gunning-Fog method uses a formula based on the average number of 
words per sentence and the percentage of “hard” words (words with 3 or more 
syllables) in the passage.
Both the Gunning-Fog and the Flesch-Kincaid give a score that is the number of 
years of education the reader must have completed to understand the text. 
Different types of writing calls for different scores. Technical subjects may 
require a higher level of education so a higher Fog or Kincaid score is 
acceptable. Informal writing may try for a score in the 7-10 range. The Flesch 
score is a percentage. The higher the value, the better the readability.

FD Word Statistics Plugin

Shows word and sentence counts plus a readability analysis of the post currently being edited using three different readability measurements.

Thomas McGee

It’s no secret that guest blogging is a powerful way to add useful content and interaction to your site. Adding to this the fact that WordPress makes it easy to track and manage the editorial and review process, it’s little wonder why so many sites, large and small use the platform to power numerous writers.
One of the difficulties, however, is making a writer clear of your site’s writing guidelines. You could send around a PDF or even create a page on your site, but that can get a bit messy.
Features include:
<ul>
<li>Change the color of the panel’s header to help match your site’s theme or to simply grab your writers’ attention.</li>
<li>Specify the post types on which you want the editorial guidelines to appear.</li>
<li>Specify the specific user roles for which you want the editorial guidelines appear.</li>
</ul>

Simple Editorial Guidelines

This plugin enables you to display a simple panel containing your editorial guidelines in the post edit admin to users of your choosing.

FD Word Statistics Plugin vs Simple Editorial Guidelines