1. Sequential Analysis
Team:
The Authors
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2. Purpose
Apply test for trial completion to each sample taken in sequence.
Applies only if the characteristics of the new distribution are known or can be estimated.
Provides minimum possible sample count to satisfy the trial requirements.
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3. Trial Satisfaction Criteria
Confidence levels
Against false negatives, 80%
Against false positives, 90%
Weibull distribution parameters
Old distribution, 5 and 30
New distribution, 5 and 40
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4. The Distributions
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5. Sequential Results
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6. Analysis Test is conclusive after five samples. Test result:
Reject the null hypothesis.
Accept that the new distribution is different from the old distribution.
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7. Validation of Weibull Parameters
13 of the new batteries, 65%, exceed lifetime of 40 days.
Vendor’s parameters are conservative.
Indicated parameter is ~42, which is better than vendor’s 40.
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8. Impact of Lost Data Postulate two lost at Day 35 To model:
Drop the best two.
Repeat the analysis.
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9. Results with Two Lost
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10. Conclusion re Two Lost
Dropping two units at day 35 has no impact on the prior conclusions.
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11. Recommendations Accept the new battery for general use.
Expect a new battery life somewhat above 40 days.
Expect about 10 extra days of battery life.
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