 But there is also a significant group of researchers who are not convinced by these analyses and who don’t think that there is any biological basis to the race concept (see, e.g., Schwartz 2001; Duster 2005, 2006; Krieger 2000; Ossorio 2005). All of these authors criticise the above studies and the geographic clusters of genetic variation they identify, mainly because of flaws in the way samples are collected (see, e.g., Duster 2015) and how the data is ultimately analysed. The latter criticism has mainly focused on the program ‘Structure’ that is used by a majority of the studies mentioned above to churn out clusters of genetic variation (Bolnick 2008; Kalinowski, 2011; Fujimura et al. 2014). A telling criticism is that while Structure can be made to report that there are five main geographical clusters that show distinctive allele frequencies and which roughly match traditional notions of race (African, Asian, European, etc.), the programme can equally be set up to report any arbitrarily selected number of genetically different groups, as the user has to specify the number of clusters they are looking for before the Structure program is applied to any actual dataset.