Network of Collaborations in Rap Music.

Often enough, many of us rejoice in the release of a new album from a popular artist. If the album belongs to the hip-hop/rap genre, it is commonplace to tout the album based on the other artist that make guest appearances in the tracks. The utility we get from the album stems in some part by the level of regard that we entertain for the collaborators themselves. In terms of network theory, there exists a network of rapper nodes connected by edges of collaboration. In 2005 researcher Reginald D. Smith sought to construct a map of this collaboration network of rappers: ( If this article feels too esoteric, Philip Ball wrote a more accessible version of Smith’s findings:(

The findings are fascinating. First of all, Smith notices that rappers in his network are connected by an average distance of less than three degrees of separation. According to Ball, this is comparable to movie actors and beats networks of both business executives and high energy physicists. What is more compelling, however, is what the layout of the network graph can tell us about why rappers choose to collaborate.

Smith looks at a characteristic of the network called “assortativity”, which is a measure of how much different groups associate with each other. Ball defines the groups as “highly connected and less connected people.” Smith acknowledges this aspect, but determines that regional groups are a more salient measure of more fundamental groups.

Although Smith’s regional grouping might show the actual factors that determine collaboration, Ball’s grouping into high/low connected probably mirrors the more common understanding of why collaborations happen. Rappers may opt to collaborate with more connected rappers because they are able to capitalize on the gravitas of their partner in order to increase the overall regard of the track. This fits with an incentive of trying to maximize the profit of the album.

The alternative is for more connected rappers to connect with rappers of less renown. This implies that the veteran rapper wants to use his/her status to launch another talent into stardom.

What might be the incentives of a top rapper to connect with a no-name? Other than region, status, label, or clique, what might be other ways to conceptualize groups of rappers?