The purpose of the study:
What constitutes a "top critic"?
In an effort to better understand how gender may influence popular film criticism, this study tracked over 2,000 reviews penned by 145 writers designated as “top critics” on the film review aggregator site Rotten Tomatoes over a two-month period in the spring of 2013. The study examined the percentages of male and female critics, the numbers of reviews they wrote during that period, and the length and nature of their reviews.
On the assumption that the rise of internet film criticism has brought a rise in women critics:
According to the Rotten Tomatoes website, writers considered top critics “must be published at a print publication in the top 10% of circulation, employed as a film critic at a national broadcast outlet for no less than five years, or employed as a film critic for an editorial-based website with over 1.5 million monthly unique visitors for a minimum of three years.”
"The bottom line":
Film critics appear to have become less, not more gender diverse over the last six years. 78% of the top critics writing in Spring 2013 were male, 22% were female.
Males accounted for 91% of critics writing for movie/entertainment magazines/websites such as Entertainment Weekly, 90% of those writing for trade publication websites such as Variety, The Hollywood Reporter and The Wrap, 80% of critics writing for general interest magazines and sites such as Time and Salon, 72% of those writing for newspaper websites, and 70% of critics writing for radio outlets/sites such as NPR.
Popular film criticism remains a predominantly male activity. Films with male directors and writers receive greater exposure as male critics are more likely to review these films than films with female directors and writers. However, while film critics tend to review higher proportions of films directed and/or written by individuals of their same sex, on average, critics do not privilege those films by writing longer reviews or awarding them substantially higher ratings. (Statistics here.)