Related Topics:
	Data Types

Multi-Phase Data

Multi-phase data types are designed for practical testing situations where failures can be corrected at the time of failure, delayed until a later time during the current phase, fixed during another phase or fixed at the end of a phase. This data type implements the Crow Extended - Continuous Evaluation model.

When used in conjunction with the growth planning folio, these data sheets allow you to compare the reliability performance of the system at each phase against the goals that were developed in the reliability growth plan.  

Different data sheets are available depending on how the testing was conducted and what information is available:

• Multi-Phase Failure Times

• Multi-Phase Grouped Failure Times

• Multi-Phase Mixed Data

See also Minimum Data Requirements for Multi-Phase Data.

Multi-Phase Failure Times

The Multi-Phase Failure Times data type is used for multi-phase data analysis with the Crow Extended - Continuous Evaluation model when the exact time is recorded for each event. It is the same as the Failure Times data type, but with the addition of the Event, Classification and Mode columns for recording the information required to use the continuous evaluation model.

The following example shows the failure times of a single system, entered cumulatively. The Event column specifies the type of event the data point represents. See Event Codes for Multi-Phase Data for information on all seven possible event types. In the following data sheet, F = failure time, AP = analysis point (i.e., a designated time at which calculations will be performed and results obtained), and I = the time when the fix for a particular failure mode was implemented. The Classification and Mode columns are for identifying and classifying the failure mode that is responsible for the failure (for F, P or Q events) or the mode that received a fix (for I events).

Multi-Phase Grouped Failure Times

The Multi-Phase Grouped Failure Times data type is used for multi-phase data analysis with the Crow Extended - Continuous Evaluation model when the time of each event falls somewhere within a specified interval. It is the same as the Grouped Failure Times data type, but with the addition of the Event, Classification and Mode columns for recording the information required to use the continuous evaluation model.

The following example shows the total test time at the end of each interval and the number of failures that occurred in each interval. The Event column specifies the type of event the data point represents. See Event Codes for Multi-Phase Data for information on all seven possible event types. In the following data sheet, F = failure time, Q = quality-related issue and P = performance-related issue. The Classification and Mode columns are for identifying and classifying the failure mode that is responsible for the failure (for F, P or Q events) or the mode that received a fix (for I events).

Multi-Phase Mixed Data

The Multi-Phase Mixed data type is used for multi-phase data analysis with the Crow Extended - Continuous Evaluation model for one-shot devices, and where some test stages (i.e., design configurations) may have only one trial and other stages may have multiple trials. For each stage of testing, both the number of trials and the number of failures are recorded (e.g., 1 failure out of 1 trial for configuration A, 2 failures out of 5 trials for configuration B, etc.). This data sheet is the same as Discrete Mixed data type, but with the addition of the Event, Classification and Mode columns for recording the information required to use the continuous evaluation model.

The following example shows the number of trials and failures in each test interval. The Event column specifies the type of event the data point represents. See Event Codes for Multi-Phase Data for information on all seven possible event types. In the following data sheet, F = failure time and PH = end of phase. The Classification and Mode columns are for identifying and classifying the failure mode that is responsible for the failure (for F, P or Q events) or the mode that received a fix (for I events).