Table of percentiles for Accelerated Life Testing

The table of percentiles indicates the age by which a percentage of the population is expected to fail at specified levels of the accelerating variable. Use the percentile values to determine whether your product meets reliability requirements or to compare the reliability for two or more designs of a product.

The table of percentiles consists of the following columns:
  • Percent, which is the percentage of a population that is expected to fail.
  • Temp, which is the temperature for which estimates are provided.
  • Percentile, which is the age by which a percentage of the population is expected to fail.
  • Standard error, which is a measure of the variability in the estimate.
  • 95% confidence interval, which provides a range of values that is likely to contain the true value of the parameter.

Use these values only with an appropriate model for the data. If the model fits the data poorly, then these estimates may not be accurate.

Example output

Table of Percentiles Standard 95.0% Normal CI Percent Temp Percentile Error Lower Upper 5 55 759.882 928.717 69.2500 8338.21 5 85 81.0926 63.2317 17.5897 373.855

Interpretation

For the electronic device data, the results show the following:
  • At the design temperature of 55°C, 5% of the CMOS RAM devices will fail after 759.882 days (approximately 2 years).
  • At the worst-case temperature of 85°C, 5% of the CMOS RAM devices will fail after 81.0926 days.
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