Developing analysis to quantitatively determine the statistical dropoff in rhyming efficiency in the “types” of songs is going to be an interesting ongoing case study. This dropoff effect, which might be named later if a large amount of songs follow this pattern, should be evident statistically. One case where we found this especially true is Eminem in ‘Stan’. Take a look at Eminem’s production across The Marshal Mathers LP:
A resounding difference in rhyming efficiency is evident between Stan and the rest of the songs on this album. Excluding Stan the average rhyme density on this album is 0.38, much higher than Stan where Eminem scored only a 0.23. In fact, that rhyme density score may be the lowest Em has ever produced on a track! This doesn’t mean Stan wasn’t a great track (it’s probably one of Eminem’s most memorable), only that purely from a rhyming POV this is uncharacteristic of what Eminem usually produces. Just listening to the song you can tell Eminem went away from the rapid fire multisyllabalic rhyming he usually employs to develop a well-crafted narrative where rhyming was secondary to the story he was trying to tell.
For the future, the difficulty lies in characterizing what is and isn’t a concept song. Some would argue that “Lose Yourself” is also a story although not as lucid, and his high rhyme scores in that song may very well be a point against this theory. It’s almost arbitrary the distinction between the two even though even amongst experienced listeners. Somehow modelling song structure and deciding what is and isn’t a concept song is almost impossible and that’s the problem we run into for future case studies.