Saturday, February 12, 2005

Another Taser death

Back to the Taser story. On the heels of a cardiac arrest in a 14 year old hit with a Taser (the boy is recovering) comes news of a death of a male "in his forties" after a Taser was used "to subdue him," also in Chicago. The local NBC station said police are conducting an "in-custody death investigation" (NBC5/WMAQ via and the police chief is putting a hold on a new order for 100 additional Tasers. On the same day the legal guardian of the 14 year old (The Department of Children and Family Services' guardianship administrator) filed a lawsuit on the boy's behalf in Cook country court (AP via TeamAmberAlert). Taser's stock price slumped.

Meanwhile, Taser International, Inc. has issued a press-release contesting a CBS News report that an Air Force study found repeated shocks from a Taser led to evidence of cardiac damage in pigs. The scientific dispute, judging from the Taser press release, relates to two scientific issues: (1) whether the blood chemistry findings in pigs subjected to repeated Taser applications (reportedly 18 applications in 3 minutes done twice, separated by an hour) are relevant to actual use; and, (2) nor are the blood chemistry findings (elevated Troponin I) relevant nor were they statistically significant, in any case.

The statistical significance objection is easily disposed of. Lack of statistical significance does not mean what the press release implies. A finding that a result is "not statistically significant" merely means you do not reject the null hypothesis (no elevated Troponin levels), not that you accept the null hypothesis, which is what Taser and its experts imply. The lack of statistical significance can easily be a consequence of a small sample size. Without seeing the actual numbers it is hard to judge. A common mistake, but a mistake nonetheless.

The objections are also difficult to assess without seeing the actual paper, presented orally at a "Non-Lethal Technology and Academic Research (NTAR) symposium" in November, 2004. (I'd like to see more of these. I have been subjected to enough lethal academic research symposia.) While I am thus not sure what to think about elevated Troponin levels in repeatedly shocked pigs in an Air Force experiment, I surely do know what to think about the mounting evidence of sudden death in human beings after being Tasered once.

I can't wait to see a press release saying the deaths are "not statistically significant" nor evidence of genuine damage.