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Test Design Assistant

Difference Detection Matrix Example

This section presents an example of how to use the Difference Detection Matrix to estimate the test time required in a reliability life test to demonstrate that a new product design will have a higher mean life than an older design.

A manufacturer plans to implement a new product design that is expected to improve the product’s mean life. The current design is expected to have a mean life of 200 hours, and the new design is expected to have a mean life of 300 hours. A reliability engineer is asked to determine, with 90% confidence, the minimum amount of test time that would be required to determine that there has been an improvement in mean life with the new design. No more than 400 hours will be available for testing, and only 10 units of each design will be available for testing.

The engineer also has some information about the life distributions for both designs. They each have a Weibull life distribution, and the beta parameter for the original design is 4.2, while the beta parameter for the new design is 3.

Follow the steps outlined below to estimate the test time required to detect a difference in mean life.

According to the above matrix, if Design 1 has a mean life of 200 and Design 2 has a mean life of 300, then a statistically significant improvement in mean life can be detected between the two after analyzing the data of a 300-hour reliability life test.

 

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