Editing Single-bullet theory (section)

===Conclusions about the single-bullet theory from the NAA analysis===
Whether the NAA data can be used to actually exclude the possibility that there were fragments from more than two bullets in the wounds and the car has been the subject of controversy.

Ken Rahn of the University of Rhode Island,<ref name="karws.gso.uri.edu">{{cite web |url=http://karws.gso.uri.edu/JFK/scientific_topics/NAA/NAA.html |title=Neutron-Activation Analysis |publisher=Karws.gso.uri.edu |access-date=August 3, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100520041055/http://karws.gso.uri.edu/jfk/scientific_topics/NAA/NAA.html |archive-date=May 20, 2010 }}</ref> a chemist and meteorologist who has a long-standing interest in the Kennedy Assassination, maintains that the NAA data excludes a "three bullet hit" and proves the single-bullet theory actually occurred. His analysis was published in 2004<ref>{{cite journal |id={{INIST|16161314}} |doi=10.1023/B:JRNC.0000040876.55194.3a |title=Neutron activation and the JFK assassination, Part I. Data and interpretation |year=2004 |last1=Rahn |first1=K. A. |last2=Sturdivan |first2=L. M. |journal=Journal of Radioanalytical and Nuclear Chemistry |volume=262 |issue=1 |pages=205–13|citeseerx=10.1.1.578.755 |s2cid=98396920 }}</ref> co-authored with Larry Sturdivan, a Warren Commission and HSCA ballistics expert.

Rahn/Sturdivan say that the possibility that the wrist fragment CE&nbsp;842 (with an antimony concentration of 797±7&nbsp;ppm) did not come from the base of the whole bullet CE&nbsp;399 (the sample from which had an antimony concentration of 833±9&nbsp;ppm) is so statistically improbable as to be excluded as a reasonable possibility.

Contradicting this conclusion, in an article published in July 2006 in the ''Journal of Forensic Sciences'' by Erik Randich and Patrick M Grant,<ref>{{cite journal |doi=10.1111/j.1556-4029.2006.00165.x |title=Proper Assessment of the JFK Assassination Bullet Lead Evidence from Metallurgical and Statistical Perspectives |year=2006 |last1=Randich |first1=Erik |last2=Grant |first2=Patrick M. |journal=Journal of Forensic Sciences |volume=51 |issue=4 |pages=717–28 |pmid=16882211|s2cid=20614842 |url=https://digital.library.unt.edu/ark:/67531/metadc890664/ }}</ref> the authors took a significantly different view of the NAA data and the metallurgical profile of the Carcano ammunition. The authors found errors in the analysis by Guinn:

<blockquote>Thus, elevated concentrations of antimony and copper at crystallographic grain boundaries, the widely varying sizes of grains in MC bullet lead, and the 5–60&nbsp;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.</blockquote>

Randich and Grant concluded:

<blockquote>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.</blockquote>

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.<ref>{{Cite web| url=http://karws.gso.uri.edu/JFK/Scientific_topics/NAA/Snyder_critique.pdf | title=On Ken Rahn's Statistical Analysis of the Neutron Activation Data in the JFK Assassination | access-date=January 25, 2007 | url-status=dead | archive-url=https://web.archive.org/web/20070226005343/http://karws.gso.uri.edu/JFK/scientific_topics/naa/Snyder_critique.pdf | archive-date=February 26, 2007}}{{full citation needed|date=December 2013}}</ref>

In August 2006 Ken Rahn wrote a response critical of the Randich/Grant paper on his website<ref name=Rahn>[http://karws.gso.uri.edu/JFK/scientific_topics/NAA/review_of_rg/Review.html Review of Randich and Grant's article on NAA<!-- Bot generated title -->] {{webarchive|url=https://web.archive.org/web/20120220085652/http://karws.gso.uri.edu/JFK/scientific_topics/NAA/Review_of_RG/Review.html |date=February 20, 2012 }}</ref> claiming that Randich and Grant did not analyse the data correctly:

<blockquote>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.</blockquote>

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.<ref>{{cite web|url=http://www.maryferrell.org/wiki/index.php/Essay_-_Commentary_on_Dr_Ken_Rahns_Work_on_the_JFK_Assassination_Investigation |title=Commentary on Dr. Ken Rahn's Work on the JFK Assassination Investigation |publisher=MaryFerrell.org |access-date=February 18, 2015}}</ref>