Logistic Model - Missile Launch Test Example

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This example appears in the Reliability growth reference.

The following table presents the results for a missile launch test. The test consisted of 20 attempts. If the missile launched, it was recorded as a success. If not, it was recorded as a failure. Note that, at this development stage, the test did not consider whether or not the target was destroyed.

1. Find a Logistic reliability growth curve that best represents the data.
2. Plot it comparatively with the raw data.
3. If design changes continue to be incorporated and the testing continues, when will the reliability goal of 99.5% with a 90% confidence level be achieved?
4. If design changes continue to be incorporated and the testing continues, what will be the attainable reliability at the end of the 35th launch?

Sequential Success/Failure Data

Launch Number	Result
1	F
2	F
3	S
4	F
5	F
6	S
7	S
8	S
9	F
10	S
11	F
12	S
13	S
14	S
15	S
16	S
17	S
18	S
19	S
20	S

Solution

1. The next figure shows the entered data and the estimated parameters.
   
   
2. The next figure displays the Reliability vs. Time plot.
   
   
3. The next figure displays the number of launches before the reliability goal of 99.5% will be achieved with a 90% confidence level.
   
   
4. The next figure displays the reliability achieved after the 35th launch.