STEP-MES Guide 02

An investigator's next challenge is to organize and integrate the input data building blocks (BBs) into a description of what happened during the occurrence being investigated. This input data management challenge, generally stated, requires investigators to:

Sequence and position input data BBs relative to each other to identify correct relationships,,
Link al data BBs to show their input to output relationships into an array depicting the flow of actions needed to produce the outcome,
Apply necessary/sufficient (N/S) logic or other tests to the data BBs and links displayed in the array,
Identify and resolve gaps in flow of linked data BBs in the array, and
Update displayed array to incorporate additional or corrected data BBs or links..

Procedures for this task are contained in this Guide. They cover manual and software-supported procedures.

INTRODUCTION

Guide 1 described how to look for and document ACTIONS as data Building Blocks to create descriptions of what happened during an investigation. This Guide describes how to sequence, integrate and test STEP-MES data Building Blocks (BBs) to identify INTERACTIONS. For many reasons, a graphical display of the input data rather than natural language is used to develop the description. This task is necessary to develop an objective, consistent understanding and description of what happened.

All these tasks take place on special actor/action matrices, a key data organization and integration element of the STEP-MES investigation technology. These matrix arrays provide for the progressive ordering, integration, display and reporting of investigation input data as the data is acquired. As each new input data item is added to the matrix, the description and explanation of what happened become more complete and coherent. Arraying data BBs on STEP-MES matrix arrays introduces new opportunities to improve investigation efficiency, effectiveness, timeliness and value. This Guide describes the tasks required to prepare and quality check STEP-MES matrix arrays. [1].

STEP-MES matrix arrays have many uses. They can be used to methodically

help investigators sequence and integrate each newly documented data BB as it is acquired during an investigation..
show up-to-the-minute investigation status during an investigation, and communicate the status as the investigation proceeds.
test the relevance of each input data BB acquired, and the logic of its matrix array position.
expose and define remaining gaps in arrays, in a "research defining" sense.
facilitate hypothesis generation and validation to close gaps and resolve uncertainties in arrays.
do objective quality control checks of investigation tasks and outputs.
accelerate completion of investigations describing what happened.
identify needs for user actions in response to the episode
shape users' reactions to satisfy their needs.
design a monitoring plan that identifies whether report user's responses produced the expected results .
support training curriculum changes to upgrade training effectiveness.
help designers improve their designs with feedback about their behavior.
share useful data among users with similar activities.
provide valid data for analyses of statistical studies, characterizations, allegations, design studies, etc.
increase knowledge base for change assessments.
upgrade operating and procedures manuals to improve their utility to users.
evaluate codes, standards and regulations effectiveness and improvement.

This examples also show how the preparation of good matrix arrays can contribute to a comprehensive organizational learning process based on efficient, objective, timely and integrated investigations of all kinds of occurrences for the organization or activity..

GUIDANCE OBJECTIVE

The objective of this Guidance is to explain how an investigator can organize and integrate investigation data by developing, testing and quality checking STEP-MES matrices.

Matrices are a progressive data organizing and integration tool, with which an investigator can achieve consistent, valid work products efficiently and quickly. The matrices become "process flow charts" describing what happened. Ideally, a STEP-MES matrix array provides a description of an occurrence in a form that allows others to reproduce it, much like a musical score or an actor's script enables reproduction of a symphony or play. This Guide describes how to position, relate, test, and present observed or recorded data BBs during investigations to arrive at complete, replicable, easily communicated and valid explanations of the occurrences.

Completed matrices describing what happened will look generally like Figure 2-1, which shows the progression of a process producing an episode outcome. In matrices, each change-producing event is an actor-action data BB created from data observed and documented during the investigation [2].

Figure 2-1 General Appearance of STEP-MES-based matrix.

BBs on the final matrix have links to show input/output relationships among BBs that produced the outcome. Uncertainties, if any, are indicated with a "?" convention, either in the BB or along the links.

APPLICABILITY

MES matrices can be used in all investigations, but they are most valuable during investigations of unprecedented, large, complicated or mysterious occurrences. For Level 1 investigations, they can be sketched to develop the narrative sections of forms. For Level 2 investigations, they facilitate a demonstration that the data BBs are presented in logical sequence. For Level 3 investigations, they provide a basis for discovering and defining problems disclosed by the evidence For Level 4 investigations, they also help organize, direct and control the tasks of however many investigators are engaged in the investigation, and screen unsupported theories about what happened, as well as discipline speculations.

The STEP-MES matrix can also be used to define new or existing system operations, and then analyze those systems for potential problems and action needs.

DATA REQUIRED

The STEP-MES matrix organizes data investigators acquire, step-by-step in a progressive way that defines the remaining data still needed as the investigation progresses. This procedure accommodates all relevant data from observers, documents, and other things, as the data are acquired. The procedure specifies criteria investigators can use to identify data relevant or irrelevant to a specific investigation. The procedure determines whether or not data acquired is necessary and sufficient through a specified testing procedure.

DATA DISPLAY

Data acquired during an investigation must be recast into data Building Blocks (BBs) before it can be used to build an STEP-MES matrix. Each new BB is placed on a matrix as it is acquired, to capture and organize the data. Time and actor coordinates on the matrix guide the placement of each BB relative to each other BB. Concurrent precede/follow and necessary/sufficient (N/S) logic tests define the interactions among BBs required to produce the outcome of interest. When completed, the matrix array will describe what happened, and the interactions will help understand what happened, with gaps in the BB array showing remaining uncertainties [3].

MATRIX ARRAY DEVELOPMENT

Matrices can be developed manually or on computers. Part I describes manual matrix development. Part II describes computerized development.

Remember, your goal is to develop a flow chart of what happened in a way that explains why it happened, using the data available. Remember also that you are using a dynamic matrix. By design, it will grow and contents may shift significantly over time as more data are acquired during an investigation. It is also a matrix that helps define additional questions to ask and data to seek as it develops.

Part A Manual Matrix Array Development.

Manual STEP-MES matrix preparation procedures during investigations require:

1. data Building Blocks created from the data acquired (See Guide 1).

2. A matrix layout space, such as a large clear wall, large chalk board or a roll of butcher paper on which to lay out the BBs as they become available. A clear floor are can also be used.

3. A method for capturing the content of interim and completed matrices, such as a camera, large xerographic or blueprint copier or coded BB filing scheme e.g., an alphanumeric designation of matrix intersection for each card.

4. If butcher paper is used, a marking pen or chalk to draw linking arrows between BBs; otherwise use masking tape for links.

Preparing The Step-Mes Matrix Array

There is no theoretical limit to the number of BBs you can add -if you can make room for them on your workspace. Manual implementation handles 30 actors easily, computers handle many more.

1. Create the matrix workspace.

Select a work surface on which you will prepare your matrix. Create a new row name containing only one actor's name to provide a separate named row along the left edge of your work surface for each actor in the BBs you add. . Place the first BB into the row with that BB actor's name on the matrix. Add more named rows as action BBs are are created and placed on the matrix.

NOTE: Refer to Guide 1 for detailed information about preparation of BBs. BBs must conform to the specifications in that Guide before they can be positioned correctly on the matrix.

2. Position BBs on the matrix

Place each BB you create on the actor's horizontal row. Position it in its correct time and spatial sequence relative to all other BBs already on the matrix. Expand the matrix time coordinate to the left or right when you add BBs, and down when you have to add an actor row.

Use the left edge of the BB to position the BB under the time it started. Keep the time scale flexible, and reposition the BBs as they are added to keep the relative timing intact throughout the investigation.

BBs can be color coded to indicate their status during during the investigation, or in final arrays if uncertainties are not resolved.

NOTE: As the matrix develops, you will find it necessary to insert new BBs between existing BBs, requiring you to expand the time-line scale. Feel free to do so at any time. Using stick-on cards makes it easy to move the events around during the matrix development process.

3. Test each BB as it is placed on matrix

As each data BB is put into place on the actor's line, mentally compare the position of your BB against the next preceding BB and the next following BB on that row, to assure it is positioned in its correct time and spatial sequence.

NOTE: This is the first data ordering step. If it fits sequentially in its logical time and spatial order, it is ready to be placed into the matrix -- tentatively. A tentative estimated duration can be indicated on the BB or matrix when needed. Note each tentative entry with a "?" to show it requires confirmation or possible future correction. The duration of BBs may become relevant when two or more BBs occurred or were occurring simultaneously during the occurrence.

Sometimes it becomes necessary to place a time line with tick marks along the top of part of the matrix, to ensure that the timing of events is distinguishable, or to show the role of time in the scenario. Any time line should be considered tentative until the final matrix testing is completed.

4. Link input/output-related BBs.

This is the first of several logic tests for your matrices. If the actor influenced subsequent actions during the occurrence (a change maker), or reacted to another actor/change maker by doing something, the BB may be relevant. As BBs are added, draw tentative arrows (lines with pointers) from one BB to any later BB that it changed. Linking BBs with arrows creates "BB pairs" or "data BBs sets." Input/output links between BB pairs may be shown in one of the following forms.

Figure 2-2. input/output-linked BB Sets

Precede/follow logic links may produce (1) linked BB pairs, or (2) converging BB sets or (3) diverging BB sets. Uncertainties are indicated by a question mark (?) between the BBs, as in (4). Uncertainties are not objectionable if they were pursued during the investigation, and if they are faithfully represented in the text of the report. (See also IQC procedure in Guide 10.)

NOTE: The linked data BB sets result from the initial (sequential) logic testing of your BB 'flow chart.' These linked BB sets form the starting point for later completeness testing and the development of needs and management action options. If timing is important, time ticks may be added along the top of the matrix.

5. Pinpoint gaps on matrix array.

If you can't draw links between BBs, the gaps between unlinked BBs point to potential unknowns in your understanding of what happened. Thus the matrix array gaps define what you need to find out as your investigation progresses. Where links are suspected to exist, an dashed arrow with an unfilled head or an arrow with a ? shows uncertainty that should be a candidate for further investigation or N/S testing. The dashed arrow or question marks can be used to assign investigation tasks as the investigation progresses, reducing the elapsed time for the investigation, and reducing investigation costs.

NOTE: The linked data BBs sets are the results of the initial (sequential) logic testing of your BB 'flow chart.' These linked BB sets form the basis for later completeness testing and the development of needs statements and candidate actions that will follow. If you can not establish links from the beginning BB(s) to the last BB or outcome, you know you have gaps in your understanding of the occurrence that may need further investigation.

6. Bridge gaps on matrix.

Try STEP-MES-Trees, (see Guide 3), simulations, tests or reenactments (see Guide 6) to bridge gaps in your logical BB flows if the gap prevents you from understanding and describing what happened and why it happened for your purposes.

NOTE: STEP-MES-Trees use BBs on both sides of the gap to bound speculation. This helps control irrelevant speculation, and helps identify specific data needed to verify each hypothesis. Change Tracking (Guide 4) and the Energy Trace and Barrier Analysis (Guide 5) can also be helpful for this purpose. The Test Planning Guide (Guide 6) describes procedures to ensure that any expenditures for simulation, testing or reenactments address specific data needs for your matrix array, reducing the risk of unfruitful efforts.

7. Perform Necessary and Sufficient tests.

This procedure tests each BB set or pair to determine the necessity and sufficiency of the data BB input-output flows that produced the occurrence outcome.

NOTE: This testing procedure reviews all the BB sets on the matrix array
to determine the necessity and sufficiency of the BBs and links shown.

Test each BB pair for the necessary relationship, then for their sufficient relationship. Keep testing until you have linked all the input BBs necessary for an output BB to occur. Then test if linked BBs are sufficient to produce the right BB Z, and add any more your find necessary, using logical reasoning. Then logically test all the links on the matrix. Begin as follows, starting with the right-most BB s on the matrix and test for links to subsequent BBs. Follow the if-then questions on the decision tree below for each BB pair on the matrix until all links have been made.

Link Arrowheads gates. Recent research has disclosed that incorporation of a necessary/sufficient test GATE (n/s gate) for each data BB link to indicate testing status or understanding provides increased rigor to this procedure. The form of the gate is in arrowheads on the links into the data BB. When arrows are created they arrowhead is empty. After all the necessary and sufficient predecessor data BBs have been coupled to the data BB block, the empty arrowheads into the BB are filled in. Empty arrowheads indicate either a need for more investigation, or an uncertainty that can't be resolved because of a lack of data.

8. Clean Up Matrix Array.

Upon completion of the Necessary and Sufficient testing procedures, you should remove all the extraneous, unlinked BBs and notations that are irrelevant to the description of what actually happened from the matrix array. What remains should be a network of linked BBs that lead from the first data BB in the scenario to the outcome. That network should be the fullest description possible from the observed data and structured hypotheses. The next step is to subject the finished matrix to a final quality control examination.

A completed matrix array will have these general elements, before the response action development process is undertaken

MES MATRIX QUALITY CONTROL REVIEW

After a matrix is checked for the necessary and sufficient logic flow, initiate a final quality control check of the work. Recheck BBs against the criteria in Guide 1. As you gain experience, you will begin to spot your own signals that an 'data BB' in a matrix array is really not a data BB at all, but rather is a conclusion, allegation or other unacceptable entry.
After a matrix array is completed, have someone who does not know anything about what happened to review the matrix array for logic errors and out-of-sequence data BBs. Also determine the completeness of the image or mental movie they can develop, as a further Q C step.
Check to be certain that all the sources referenced in the BBs are verified against the BBs, and are on hand and retrievable.
If the matrix array review indicates problems or misunderstanding, ask the persons who should know the operations to look at the matrix array and verify your entries and the logic of the BB flow and links. This review usually produces valid data BB flows and descriptions, or additional BBs after the are subjected to the necessary and sufficient tests.
Review each ? on the matrix array and verify that all sources of data have been exhausted, or that the decision not to pursue remaining uncertainties, gaps or unknowns has been accepted by the investigation sponsor (the person paying for it.)
After the quality control checks have been completed, the investigator(s) should sign the matrix array to denote that it has been checked and found satisfactory, and that it is finished.

Upon completion of the final quality control steps and the signing of the matrix array by its developers, the matrix array is ready for subsequent uses.

PART B. COMPUTERIZED MATRIX ARRAY DEVELOPMENT

The process of developing BBs, positioning them on the matrix, linking them and testing sets for input-output relationships can be supported by some software applications. However, users should be acquainted with the manual implementation described above to guide their use of any software.

Computer graphics applications have developed to the point that they can be used to create animated descriptions of the behavior of objects in accidents. Thee animations are created in much the same manner as the STEP-MES arrays, with one building block at a time. In the In the aviation field, particularly, the behavior of an aircraft in flight has been reconstructed from fight data recorders and displayed as a computer-generated movie. In significant cases, where the behavior of objects is important to display, the "mental movie" created by the investigator can be "transferred" to a computer using these computer graphics animating applications. The displays can also be used to aid in hypotheses. Look for expended use of this capability in the future.

Once made, these animations of the occurrence can be used for training, design considerations, and other purposes.

Users are invited to provide feedback on software applications that would be useful to other users.

I had prototype softward called Investigation Catalyst developed to see if the STEP-MES system could be implemented in the early 2000s for Macs. It had a full help menu and tutorials, supported local and remote data entry, BBcsequencing, i/o BB linking, remote data BB array displays, various tabular and structured i/o BB printouts, data reporting including tables and i/o displays, auto glossary creation, problem notation, jump maps and other features, The beta2 version of the software was made open source and is posted at https://code.google.com/archive/p/meslib/ for anyone intersted.

ENDNOTES

[1] See also Hendrick, K. and Benner, L., INVESTIGATING ACCIDENTS WITH STEP, Marcel Dekker Inc., New York, NY 1987. The acronym STEP (from Simultaneous Timed Events Plots) has been used to describe these matrices. However, while descriptive of the format, STEP does not communicate the full breadth of functions served by the matrices, so the broader term STEP-MES technology-based matrices or STEP-MES MATRIXS is the term of choice used in this set of Guides.

[2] The format shown in this Guide differs from the format presented previously, because these Guides distinguish the description development tasks separately from the needs and recommendation development tasks. A completed marked up matrix is illustrated in the User Action Development Guide 10.

[3] STEP-MES matrix arrays differ from Events and Causal Factors (E&CF) charts in several ways. STEP-MES uses only BBs with a consistent structure content and grammar, demands relative BB timing, uses special link and logic tests, is built progressively and focuses on input/output actions - no conditions required - on the matrix. Conditions do not produce the next change, although they may be a necessary input; the action(s) that produced the conditions produced it, and they should be the primary interest of the investigator. Typical E&CF charts are technically obsolete today.

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Guide 2 GUIDANCE FOR SEQUENCING AND INTEGRATING INVESTIGATION INPUT DATA BBs

Table of Contents

MANAGING INVESTIGATION INPUT DATA

INTRODUCTION

Guide 2

GUIDANCE FOR SEQUENCING AND
INTEGRATING INVESTIGATION INPUT DATA BBs