Specify the retirement information for exact failure data. If you have interval data, you cannot use a retirement column.
- Retirement time at largest time for system: Select this option if the largest time for each system is the retirement time for the system.
- Failure truncated systems: Select this option if you have only failure-truncated data. A failure-truncated system is retired after a certain number of failures occur. The system is retired immediately after the final failure. The largest time for each system is the retirement time. This time is a failure time for the system.
- Time truncated systems: Select this option if you have only time-truncated data. A time-truncated system is retired after a specified period of time. The largest time for each system is the retirement time. This time is not a failure time for the system.
- Retirement time defined by retirement columns: Select this option to define the retirement time when you have both failure-truncated and time-truncated systems.
- Retirement columns
- Enter the retirement column or columns. A retirement column indicates whether each time is a failure time or a retirement time. Retirement indicators can be numeric, text, or date/time. Each system must have a retirement time. If you enter multiple columns, the first retirement column that you enter is paired with the first data column, the second retirement column that you enter is paired with the second data column, and so on. All retirement columns must have exactly two distinct values.
- Retirement value
- Enter a value to indicate which value in the retirement column represents a retired system. Text values must be contained in double quotation marks. The retirement value that you enter will apply to every retirement column. If you do not enter a value, Minitab uses the lowest value in the retirement column as the retirement value and assumes that the higher value is a failure/repair time.
Note
If you provide multiple retirement columns, and at least one of those columns corresponds to systems that are only time truncated, then you must specify the retirement value.
The following worksheet shows how the data can be interpreted differently depending on how they are truncated and whether a retirement column is used. If the data in the Time column are failure-truncated only and you do not enter a retirement column, then Minitab assumes that system 1 was retired after a failure at 9 hours. If the data in the Time column are time-truncated only and you do not enter a retirement column, then Minitab assumes that system 1 was retired at 9 hours, not due to failure. If the data are both time-truncated and failure-truncated, and you enter a Retirement column, then Minitab assumes that system 1 failed at 1 hour, failed at 5 hours, and was retired at 9 hours.
| C1 |
C2 |
C3 |
| Time |
System |
Retirement |
| 1 |
1 |
1 |
| 5 |
1 |
1 |
| 9 |
1 |
0 |
| 4 |
2 |
1 |
| 7 |
2 |
1 |
| 10 |
2 |
1 |
| 8 |
3 |
1 |
| 9 |
3 |
1 |
| 11 |
3 |
0 |
