Determine sample size requirements for estimating parameters

To estimate the sample size that you need to estimate the scale parameter (Weibull or exponential distribution) or the location parameter (other distributions), use an estimation test plan. Use the plan to calculate the sample size you need to estimate the corresponding percentile of the distribution.

Choose Stat > Reliability/Survival > Test Plans > Estimation.
In Distribution, choose a distribution.
To estimate the location parameter for a normal distribution, choose Normal.
Under Specify planning values for parameters, enter one value for the exponential distribution or two values for the other distributions.

Under Parameter to estimate, choose Percentile for percent, then enter a percentage between 0 and 100.

For example, estimating the location parameter for the normal distribution is equivalent to estimating the 50^th percentile of that distribution. To estimate the location parameter for the normal distribution, enter 50.

Use the following table to determine the percent that corresponds to the scale or location parameter for the chosen distribution.

Distribution	Parameter to estimate	Percent
Normal	μ	50%
Lognormal	exp(μ)	50%
Logistic	μ	50%
Loglogistic	exp(μ)	50%
Smallest extreme value	μ	1 - e^(-1) ≈ 63.2121%
Weibull	θ	1 - e^(-1) ≈ 63.2121%
Exponential	θ	1 - e^(-1) ≈ 63.2121%

In Precisions as distances, choose Upper confidence bound to estimate or Lower confidence bound to estimate and enter the precision you would like.