flakes both preparing the core by shaping and removing the roughened exterior of the cortex (Sheets 1978:9). The percentage frequency of cortex is an important statistic to help identify lithic production areas. A low incidence of cortex would indicate quarry preforming (cortex removed at the quarry, not at the site). One specific type of debitage analysis is mass analysis. Mass analysis is based on analyzing debitage populations based on their size distribution across specified size grades. Ahler (1989) conducted an experimental replication under some technological settings and classified debitage into five groups according to their size, Discriminant analysis (by SPSS DISCRIMINANT function) was applied to compare mass analysis data sets for these five experimental data groups. He then compared the counts and weights of experimental samples with debris from two prehistoric workshop sites in western North Dakota. The result shows the experimental data sets can explain the technological composition of archaeological samples. Samples from several other sites also are applied this method and derive clear discriminant results. Especially in a specific function site, such as Legacy site a Late Woodland age camp in the Missouri breaks, associated with bison kill/butchering, the low frequency of cortex and a specific flake ratio (G4:Gl-3 ) data indicate that a soft hammer small flake tool production, which is similar with experiment result. Although this process has been used in many studies, Andrefsky warns of the potential problems associated with the many assumptions made while employing this analysis. One in particular that he draws attention to is the possibility of differences in debitage populations based on individual variation of the artifact maker; in his example, three different knappers all using bipolar core reduction have different percentages of size grade 3 debitage (5.2%, 13.2%, and 10.2%). These differences indicate that individual variation can be influential in the size distribution of debitage and should be kept in mind if mass analysis is being employed. The reason for which Andrefsky believes mass analysis have become so popular is due to the process's ease of use and speed. Andrefsky even quotes Ahler that between individual specimen analysis and mass analysis, mass analysis has the advantage because of four reasons: 1) biases are eliminated because mass analysis looks at the entire assemblage; both completed and fractured. 2) Because mass analysis doesn't require looking at each artifact, it is very rapid and efficient. 3) debitage biases based on the sample's size