Transcript Multilinear Events Sequencing (MES)

Multilinear Events Sequencing
MES incorporates timelines into
sequential diagrams, providing a
scale that parallels the sequences of
events to show the time relationships
between events and the incident.
 The method distinguishes between
actors, actions and events.
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Definitions
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An event is one actor performing one action
Primary Events are directly tied to the accident sequence
Secondary Events are events that play a role in the accident
but are not directly part of the accident sequence
Secondary Events are tied to the Accident Sequence of
Events with vertical lines
Conditions differ from events insofar as they:
(a) describe states or circumstances rather than happenings
or occurrences and
 (b) are passive rather than active
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Cause Mapping
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Cause Mapping utilizes the fundamental principles of
systems thinking to identify the basic cause and effect
relationships of any problem.
Cause Mapping is a 3-step problem solving process
for defining, analyzing and solving any type of
problem.
The steps in Cause Mapping are:
Step 1: Problem: Outline the problem by asking who, what, when, and
where?
Step 2: Analyze: Develop the Cause Map beginning with the unwanted
outcome. Working to the right, identify the preceding cause(s)
Step 3: Solutions: Identify the best possible solutions.
Multilinear Events Sequencing (MES)
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Designed to detect hazards arising from the time
relationship of various organizational activities.
MES-diagrams
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A MES-diagram portrays the
accident being investigated as a
sequence of causally connected
events, which represent activities.
Event Blocks
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Each event block contains the
following information about its
event description of the action;
Actor:
the object or person that
performed the action
Time of event
Causation
Event blocks are connected via
arrows that represent causation.
 If event X was necessary for event
Y to occur, then MES-diagram
contains an arrow from X to Y
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MES Diagrams
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MES-diagrams have two axes
The horizontal axis represent time
 The vertical axis lists actors involved in the accident
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Event blocks are placed on the diagram according
to their time and actor
Any relevant information that does not fit event block
structure can be placed on MES-diagram as a
condition
A condition is an oval with some text inside
A condition is linked to an event block via an arrow
MES Diagram
MES-diagram Process
Events are identified
 Causal connections between
events are identified
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Counterfactual reasoning
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Counterfactual reasoning is a way to
establish causal dependency between
events
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may define a cause to be an object
followed by another, and where all the
objects, similar to the rest, are followed by
objects similar to the second.
 Or, in other words, where, if the first object
had not been, the second never had
existed.
Acid Test of MES
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To determine if the MES charting is correct, the
investigator must determine:
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the actors, events, actions, and sequencing, will
the scenario developed result in the same outcome?
 If the answer is yes, then the MES is complete
 If the answer is no, then there are gaps in the MES
Using MES for Accident Investigations
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Examine each arrow (causal links between events)
Develop countermeasures at each causal link
Activity 5
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Perform a literature search and identify one
accident scenario or use a work accident you are
familiar with.
Remove all descriptors (ie: company name,
employee names, etc)
Using the scenario, apply the Multilinear Events
Sequencing technique to develop a causal map of
the accident.
Complete the assignment and upload the activity
to your instructor through D2L by the due date in
the course syllabus.