Multiple Failure Modes - Right Censored Data
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Many systems have more than one cause of failure. To obtain statistics for each failure mode as well as for the overall system, you must record the causes of system failure.  

You must have at least two columns of data: failure times and the corresponding failure mode. You can also have frequency and censoring columns.

Months to failure

Failure mode

Censor

 

50

60

53

40

51

99

35

55

.

.

.

and so on

Motor

Impeller

Impeller

Impeller

Motor

 

Foreign Object

Foreign Object

.

.

.

and so on

F

F

F

F

F

C

F

F

.

.

.

and so on

The Censor column contains the corresponding censoring indicators: F designates an actual failure; C designates a unit that was removed from the test before failure.

Note

Represent right-censored observations with an asterisk (*) in a numeric failure mode column and with a space in a text column.

Minitab omits rows with missing values from the calculations unless the missing values represent censored observations.