To make quantitative statements about music you need to have data; lots of it. Guitar tab websites have tons of information about the chord progressions that songs use, but the quality is not very high. Just as important, the information is not in a format suitable for gathering statistics. So, over the past 2 years we’ve been slowly and painstakingly building up a database of songs taken mainly from the billboard 100 and analyzing them 1 at a time. At the moment the database of songs has over 1300 entries indexed.
Knowing these patterns can give one a deeper more fundamental sense for how music works"