Home of the Soul Cookie

From a tidbit in iMDB’s Studio Brief:

Here’s the Formula for Movie Success

A University of London lecturer claims to have discovered the essential formula for creating hit movies, the Liverpool Daily Post reported today (Wednesday). According to Sue Clayton, who is also a movie director and a member of the British Film Council, films that have become hits have 30 percent action; 17 percent comedy; 13 percent “good versus evil,” 12 percent love/sex romance; 10 percent special effects and 10 percent music.

Now, are those percentages by weight or by volume?