Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!ncar!unmvax!uokmax!occrsh!fang!att!cbnewsc!cbnews!cbnews!military From: tewok@TIS.COM (Wayne G. Morrison) Newsgroups: sci.military Subject: Re: patriot missile failure Message-ID: <1991Jun28.023930.29959@cbnews.cb.att.com> Date: 28 Jun 91 02:39:30 GMT Sender: military@cbnews.cb.att.com (william.a.thacker) Organization: AT&T Bell Laboratories Lines: 49 Approved: military@att.att.com From: Wayne G. Morrison In a recent article, John Boone (boone@ida.org) said the following: > I think claims that the Patriot software was "buggy" are somewhat of a > knee-jerk reaction, given the overall performance of the system. The fact is, > any significantly complex system has some bugs. With our present state of > technology, it's just a question of how often (and under what conditions) the > bugs manifest themselves. I would not call a system with a +95% performance > rate (in shooting down extra-supersonic missiles) - a buggy system. For unspecified reasons, I have not gotten a daily paper for a few months and so I don't know what sort of numbers the DoD has released about the usage of the Patriot system during the Gulf War. However, I have heard from a reliable source that the Patriot system did far worse than the above mentioned +95% performance rate. Depending on which number is accurate, the Patriot's performance rate was 15% - 18%. (The "depending on which number is accurate" comment is a reflection of my memory -- I don't remember which of two numbers was actually given to me.) The performance rate function I was given was: performance rate = (# of SCUDs within Patriot's coverage envelope) / (# of Patriot missiles fired) Filling in the numbers gets either: 15% rate = 27 SCUDs / 180 Patriots or 18% rate = 27 SCUDs / 150 Patriots The 27 SCUDs may be off by a bit, but I think that's a pretty close number. One of the first things my college statistics professor taught me is that statistics can be used to say anything you want them to say and are, therefore, useless. I suppose the Mr. Boone's +95% performance rate can be derived from something like the percentage of SCUDs that the Patriots intercepted. I'd like to know how that number was generated and I'd also like to know if that's what the DoD has been saying. I guess the performance of the Patriots all comes down to what you're trying to show. +95% SCUD-killing rate or the effectiveness-rate (for lack of a better term) of the Patriots. If you had the system cost, you could even give it in terms of which system was more cost-effective. Wayne Morrison PS. I realize that my information is not likely to be seen as particulary trustworthy since I can't give precise numbers.