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The Most Trusted Audio Brand Worldwide Industry: Consumer and professional audio electronics Founded: 925 Products: Microphones, wireless microphone systems, headphones and earphones, mixers, conferencing systemsģ Agenda Intro to Reliability Selecting a distribution Testing to failure Right censoring Testing to failure Arbitrary censoring Accelerated testing Single Factor Accelerated testing Multiple factors Summary QuestionsĤ Quick Intro to Reliability Reliability = quality over time Field failures Failure modes Testing to replicate failure modes Measuring time to failure Attempt to predict failure rateĥ Quick Intro to Reliability Probability Distribution Function (PDF) A function that describes the relative likelihood for this random variable to take on a given value Integral over a range = probability of the variable falling within that rangeĦ Many Distributions Quick Intro to Reliabilityġ0 Parameters Quick Intro to Reliability Threshold / Location: The 3 rd parameter shifts the zero point Forced to zero in a: 2-Parameter Lognormal Normally called just Lognormal -Parameter Exponential Normally called just Exponential 2-Parameter Weibull Normally called just Weibull 2-Parameter Gamma Normally called just gamma 2-Parameter Loglogistic Normally called just Loglogistic (not represented on straight line cumulative probability plot)ġ1 Quick Intro to Reliability Testing to Failure: What is censoring? Some tests will not be able to run to the end due to time constraints = Right censored data or Suspended data Some tests cannot be continuously monitored = Arbitrary censoringġ3 Many Distributions and more which one? Distribution IDġ4 Distribution ID What do you know about your data? Reliability data starts at time=0 Is it bound? Bound by zero (or something greater) Any historical references? Weibull, Lognormal, Gumbel (extreme value) Finally Does it look like it fits?ġ5 Distribution ID Statistics to look at: Anderson-Darling test: How well your data fits the PDF Smaller fits better p value: Student s t-test does your data fit the PDF? H 0 = data fits the distribution p is low, the null must go! i.e. 2 Introduction Rob Schubert - Corporate Quality/Reliability Engineer at Shure Inc.