Estimation of an adequate sample size drawn from the population is necessary to draw educated and meaningful conclusions on how durable a part will be over the course of its life. This case study uses the example of a glycol battery cooler to illustrate the collection and analysis of attribute data to determine the likelihood of cyclic loading causing a leak in the cooler’s fluid fittings whose braze joints have variable quality. It will then explore how valid the conclusions drawn from this test are and what type of sample sizes would be needed to draw better conclusions of the expected failure rate of the population of parts from which the sample of parts have been taken from.

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