boundaries, the widely varying sizes of grains in MC bullet lead, and the 5–60 mg bullet samples analyzed for assassination intelligence effectively resulted in operational sampling error for the analyses. This deficiency was not considered in the original data interpretation and resulted in an invalid conclusion in favor of the single-bullet theory of the assassination. Randich and Grant concluded: The end-result of these metallurgical considerations is that, from the antimony concentrations measured by VPG [Vincent P. Guinn] in the specimens from the JFK assassination, there is no justification for concluding that two, and only two, bullets were represented by the evidence. The conclusion of Randich and Grant had been advanced earlier by Arthur Snyder of the Stanford Linear Accelerator Laboratory in a paper written in 2001. In August 2006 Ken Rahn wrote a response critical of the Randich/Grant paper on his website claiming that Randich and Grant did not analyse the data correctly: Both sections of the article failed to make their case. The metallurgical section contained a huge gap in its logic (proposing an explanation but failing to support it quantitatively), and predicted at least two features of the elemental data that were the opposite of that actually observed. The statistical section started well, but stumbled when it confused heterogeneity with analytical uncertainty and when it used confidence intervals instead of difference in means to assess the separation of the two groups of crime-scene fragments. Fixing these two errors gave the opposite result, i.e., confirmed that the groups were distinct. Patrick Grant defended his and Erik Randich's paper against Rahn's critique in an article entitled Commentary on Dr. Ken Rahn's Work on the JFK Assassination Investigation and posted it on the MaryFerrell.org website. Forensic use of compositional bullet lead analysis The technique used by Guinn to analyse the bullet lead from the JFK assassination was a form of what has become known as Compositional Bullet Lead Analysis (CBLA). Until 2004 the FBI used this technique to determine whether a crime scene bullet lead sample came from a particular box of ammunition or a particular batch of bullets. Guinn claimed that with the JFK bullet fragments, the technique could be used to identify the exact bullet the fragments came from. However, the validity of CBLA was discredited in a 2002 paper ("A Metallurgical Review of the Interpretation of Compositional Bullet Lead Analysis", (2002) 127 Forensic Science International, 174-191) co-authored by