Accelerated Life Test Plans - Stress Levels
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Stat > Reliability/Survival > Test Plans > Accelerated Life Testing > Stresses

You must enter the design and test stress levels. By default, Minitab will determine an "optimal" allocation of units across stress levels. Alternatively, you can provide the allocation. See Searching for the Optimum Proportions.

Dialog box items

Design stress: Enter the stress level for normal use conditions.

Test stresses: Enter one or more fixed test stress levels. You can type the stress levels, enter stored constants, or enter columns. Type or enter stored constants if the test stress levels are for a single test plan. Use columns for a set of test stress levels for a series of test plans. Each column represents a separate set of test stresses.

User Defined Allocations for each Stress Level

Percent Allocations: Enter the percent of units to test at each test stress level. You can type the percent allocations, enter stored constants, or enter columns. Type or enter stored constants if the percent allocations are for a single test plan and sum to 100%. Use columns for a set of allocations for a series of test plans. Columns must be the same length as the columns of test stresses and must sum to 100%.

Search for the Best Allocation for each Stress Level: Check to have Minitab find the optimal allocation for each stress level. The optimal allocation yields the smallest asymptotic variance of the parameter to be estimated.

Step length in search: Enter a value between 0.01 and 0.5  to use to go through the range of each test stress. The default is 0.05. See Prefixed Ranges and Default Steps.

Number of "best" plans to output: Enter the number of test plans for Minitab to display. The default is 3. See Efficiency and Accuracy of Accelerated Life Test Plans.