“…Assigning observations to groups is a common goal in psychological research, whether it is via mixture modeling (McLachlan & Peel, 2000) or cluster analysis (Everitt et al, 2011). As such, much effort has been made in determining how to assess the performance of traditional clustering approaches (Bruzzese & Vistocco, 2015; Hofmans, Ceulemans, Steinley, & Van Mechelen, 2015; Steinley, 2003, 2006; Steinley & Brusco, 2007, 2008a, 2008b), mixture modeling (Steinley & Brusco, 2011; Vrbik & McNicholas, 2015), latent class analysis (Brusco, 2004), and latent profile analysis (Steinley & McDonald, 2007), among many other approaches such as divisive clustering (Kovaleva & Mirkin, 2015), facility location problems (Brusco & Steinley, 2015), and social network analysis (Brusco & Doreian, 2015). The measure of choice for determining the adequacy of a partition of observations into groups is the adjusted Rand index (ARI; Hubert & Arabie, 1985).…”