the normalized pairwise variability index (npvi) , originally developed for the analysis of speech prosody, has been shown to be a useful tool in the analysis of the rhythmic variability present in individual melodies and melodic corpuses (Patel & Daniele, 2003a; Huron & Ollen, 2003; Patel, Iverson, & Rosenberg, 2006). Here we suggest a number of rhythmic refinements for the application of the nPVI in musical contexts. These include (a) applying the nPVI metric to higher levels of rhythmic structure, (b) taking metrical structure (duple versus triple) into account, and (c) using alternative codings for surface durations. A reanalysis of the data from Patel & Daniele (2003a) is given as a demonstration of the utility of these refinements for the analysis of musical styles and repertoires; other possible refinements are discussed.