causal tree (See root cause analysis)

A causal tree is a diagram of the event that includes all possible causes and recoveries gathered during the event’s investigation. The tree displays critical activities and decisions that occurred during the event in both logical and chronological order. By reconstructing the event, the causal tree shows the variety of the underlying or root causes.

At the top of the causal tree is the consequent event, which is described in terms of the event’s consequences— harm that either did happen (misadventure) or could have happened (no harm event or near miss).

Below the consequent event, the tree is divided into two sides, the failure side and the recovery side.
The limbs of the causal tree are made up of antecedent events, which are actions that reveal what prompted or influenced the consequent event. These events are displayed in both logical and chronological order.

By continuing to ask "why" of each event (beginning with the consequent event), all relevant antecedent events, as well as the root causes of those events, are revealed.

Once the root causes are identified, they can be used to provide a more realistic view of how a system is actually working, as well as contribute to the creation of effective and lasting solutions.

(See the Investigation path of the Process Overview lesson in the QA SysOp Training.)

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cause codes (See root cause codes).

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Classification and Description

Classification and Description is one of the six major tasks within the MERS-TM process. Because a central goal of MERS-TM is consistency and uniformity of descriptive information, Classification and Description are important functions within the event management process.

Assigning brief descriptions and/or codes to types of events and root causes makes the process of collecting, organizing, searching, and interpreting the data.

MERS-TM requires two types of coding, which are assigned at various points in the MERS-TM process::

1. Event coding – assigning codes to an event that indicate where in the work process the event was discovered and where in the process it actually occurred
2. Root cause coding – assigning codes to the root causes identified through the root cause analysis

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codes (See event codes or root cause codes)

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Computation

Computation is one the six major tasks or steps within the MERS-TM process. Computation provides a way to look at how often a particular type of event has occurred over time and to show comparisons among events. This step allows management to see patterns or trends, focus on areas of risk, and monitor any changes that have been implemented within the organization.

MERS-TM provides an easy, straightforward method for viewing event data in multiple formats and from various perspectives. Two major tools have been designed to help compute and represent the event data:

• MERS-TM Report Generator
• Event comparison software

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consequent event

The consequent (discovery) event is located at the top of the causal tree.

The consequent event is described in terms of the event’s consequences:

• harm that either did happen (misadventure)
• harm that could have happened (no harm event or near miss)

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context dependence phenomena