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The general approach is to solve for “k” in the tolerance interval formula.

\begin{array}{l}{\bar{X}+\mathrm{k}^{\star} \mathrm{S}<\text { Upper Specification }} \\ {\bar{X}-\mathrm{k}^{\star} \mathrm{S}>\text { Lower Specification }}\end{array}

Sample Size for Individual Calculator

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Example

The peel test measures the peak force required to separate a pouch seal. The peel strength for a new pouch seal needs to be a minimum of 4N to ensure a sterile barrier. The risk is determined to be major requiring a confidence level of 95% with a reliability of 90%. Data from the packaging qualification showed that the standard deviation was 0.2N with a mean of 4.5N. What is the sample size for the package validation study to show that the peel strength is a minimum of 4N?

The general approach is to solve for k in the tolerance interval formula, then find the accompanying sample size for the level of confidence and reliability (coverage for tolerance intervals).

NOTES

Often we desire a sampling plan that reflects the distribution of the individual units and not the mean performance. Utilizing the tolerance interval, we can find the sample size needed to have a certain level of confidence with a certain level of reliability.

Sample Size for Individual Calculator

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Sample Size for Individual Calculator
Confidence level:
Reliability:
Estimated Standard Deviation:
Estimated Mean:
Lower Specification:
Upper Specification:
Sample Size:
Reset

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