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Article #35frequency and specification
From: Pierre Dupont
Date: Wed, 28 Aug 2002 16:44
Date: Wed, 28 Aug 2002 16:44
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2343 bytes
The data : - A temporal serie : (x1, x2, ., xn) - Time between two observations : delta - specification : X < b How i can change delta to be able to react enough early to not have a point out of the specification? Intuitively, if I increase the frequency , i can react more quickly. But. Formelly Hypothesis : random observations The variable X has a mean m and a standard deviation sigma. Notations : X = variable delta = time between two consecutive observations lambda = failure parameter L = lenght before OS (Out of Specification) The expectation of L is: 1/p where p=P(X>b). For simplicity, I suppose that the only failure is a shift of the mean where the mean pass from m0 to m1 = m + lambda* sigma. The average time before an OS if no failure (lambda = 0) is : Delta * E0(L). For a failure lambda, the average time before an OS is: Delta * E(L;lambda). If the frequency change from Delta to Delta1 = c* Delta, the average time before an OS is :Delta1* E(L;lambda) = c *Delta* E(L;lambda). If the variable has a large deviation, or is too close of the specification, the average time before an OS is little. So, intuitively, I increase the frequency of the observations. But the observations are independent, so the average length before an OS is constant and the average time before an OS decreases ! Where is the bug ?
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 10468c,9f13b86d4fa3da99,start X-Google-Attributes: gid10468c,public X-Google-ArrivalTime: 2002-08-28 09:52:31 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!sn-xit-02!sn-xit-01!sn-xit-04!supernews.com!news.maxwell.syr.edu!opentransit.net!newsfeed.online.be!skynet.be!skynet.be!louie!not-for-mail From: "Pierre Dupont" <dupontpierregy@skynet.be> Newsgroups: alive.statistics Subject: frequency and specification Date: Wed, 28 Aug 2002 18:44:19 +0200 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Lines: 54 Message-ID: <3d6cfdc8$0$189$ba620e4c@news.skynet.be> Organization: -= Skynet Usenet Service =- NNTP-Posting-Host: 80.200.163.242 X-Trace: 1030553033 reader0.news.skynet.be 189 80.200.163.242 X-Complaints-To: abuse@skynet.be