\section{Conclusion}

The Grateful Dead were an American music phenomenon that influenced multiple generations of music lovers. For 30 years, the Grateful Dead made a career out of an unrelenting tour schedule that took them around the world, and, unlike typical bands, took their fans with them. It is now 43 years since the band started and with the use of online music providers and services, it is possible to track the listening behavior of the many Grateful Dead fans in the world today. This article presented an analysis comparing the popularity of Grateful Dead songs as identified by both how many times they were played in concert and how many times they were listened to by members of the last.fm online music service. The correlation between concert plays and fan listens is strong, but not perfect. Those songs that existed as outliers to a perfect correlation were analyzed to understand what made these songs deviate from the model. These deviations can be understood by changes in the band, by live performance album releases, and by the very nature of the songs themselves.

There is much to be learned about American concert tour culture and the bands that bring this culture to fruition \cite{concert:black2007}. Perhaps more than any other band, there exists large amounts of Grateful Dead data that go beyond set lists to include lyrics, chord progressions, concert reviews, and history. Many books have been published about the Grateful Dead and albums continue to be released 13 years after their final concert in 1995.  Without a doubt, the Grateful Dead have made a profound impact on that which is American rock music.