While I did my best to find as many songs as I could from each decade and from a range of genres, I was ultimately limited to what I could find from internet searches and my own knowledge of song lyrics in the amount of time I had. A more extensive search and analysis was beyond the scope of what I could do as an individual in a relatively short amount of time. Therefore, the amount of songs included in the 2010s could potentially be a reflection of my age influencing which songs I knew. However, if I removed the songs from that decade that I chose specifically because I thought of them (rather than because I found them mentioned elsewhere), only 4 of the 33 in the overall analysis would be excluded. I'm reasonably confident that my data fairly represents the evolution of drugs in lyrical content, but I don't dismiss the potential biases I could have introduced to the data used. Additionally, I didn't include songs with lyrics with debatable meanings (e.g., "Silvergun Superman" by Stone Temple Pilots) or that are generally interpreted and accepted to be about drugs despite confirmation from the artist that it is about something else (e.g., "Lucy in the Sky with Diamonds" by The Beatles). I also did not include songs that had a lot of featured artists, as the drugs mentioned and the association in the lyrics tended to change depending on the artist.