Optimum allocations test plans for Accelerated Life Test Plan

Minitab evaluates the resulting test plans and displays the best plans with respect to minimizing the standard error of the parameter of interest. By default, Minitab displays 1 test plan. The best plan is the one with the smallest variance.

If little difference exists in the standard error of the parameter of interest across test plans, choose the plan that would yield more failures or is the least expensive to execute.

Example output

1st Best “Optimum” Allocations Test Plan

Test Stress	Censor Time	Percent Failure	Percent Alloc	Sample Units	Expected Failures
85	90	8.2508	63.3333	63	5
105	90	29.1956	3.9583	4	1
125	90	70.0000	32.7083	33	23

Interpretation

For the capacitor data, the allocation of 100 units that minimizes the variance of the 360-day reliability is:

Test 63 units at 85 degrees.
Test 4 units at 105 degrees.
Test 33 units at 125 degrees.

The settings for this test plan time censoring at 90 days, so the plan is that the test continues for 90 days.

The estimated standard error of the 360-day reliability is 0.338939.