921 Chapter 4 - Basic Methodology

Question 1

What is the nature of fire investigations?

Answer 1

A complex endeavor involving skill, technology, knowledge, and science. It’s a compilation of factual data and analysis, expressing opinions or conclusions objectively, truthfully, and without expectation bias, preconception, or prejudice.

Question 2

What is the systematic approach in fire investigation?

Answer 2

An approach recommended and based on the scientific method used in physical sciences. It provides an organizational and analytical process that is desirable and necessary in a successful fire investigation.

Question 3

What are the 7 steps of the Scientific Method?

Answer 3

1. Recognize the need (identify the problem)
2. Define the problem (determine how it can be solved)
3. Collect data (gather empirical information)
4. Analyze the data (examine and understand meaning)
5. Develop hypotheses (inductive reasoning)
6. Test the hypotheses (deductive reasoning)
7. Select final hypothesis

Question 4

What is empirical data?

Answer 4

Information about the fire or explosion incident that is known through observation, experimentation, or direct data-gathering means. It is based on observable experience and is capable of being verified or known to be true. Data collection can occur at nearly every stage of the fire investigation.

Question 5

What makes data analysis essential?

Answer 5

Analysis is an essential step that must take place before the formation of the final hypothesis. The identification, gathering, and cataloging of data does not equate to data analysis. Analysis is based on the knowledge, training, and experience of the individual doing the analysis. If the investigator lacks expertise, assistance should be sought.

Question 6

What is inductive reasoning in fire investigation?

Answer 6

The process where the investigator produces hypotheses explaining fire phenomena, fire patterns, fire spread, identification of origin, the ignition sequence, and the fire cause or causes. These hypotheses should be based solely on empirical data collected through observation and developed into explanations based on the investigator’s knowledge, training, experience, expertise, and research.

Question 7

What is deductive reasoning in fire investigation?

Answer 7

Testing the hypothesis by the principle of comparing it to all known facts and scientific knowledge. The investigator does not have a valid or reliable conclusion unless the hypothesis can stand the test of careful and serious challenge. The goal is to disprove or refute the hypothesis (falsification) rather than simply finding supporting data.

Question 8

How can hypotheses be tested?

Answer 8

Through three methods: 1) Conducting experiments, 2) Applying accepted scientific principles analytically, or 3) Referring to scientific research of others. The investigator must ensure that the conditions, circumstances, and variables of the research match those of the hypothesis sufficiently.

Question 9

What should happen if a hypothesis is refuted?

Answer 9

If the hypothesis is refuted or not supported, it should be discarded and alternate hypotheses should be developed and tested. This may require the collection of new data or the reanalysis of existing data. Testing should continue until all feasible hypotheses have been examined.

Question 10

What makes a hypothesis invalid?

Answer 10

A hypothesis that is incapable of being tested either physically or analytically is an invalid hypothesis. A hypothesis developed based on the absence of data is an example of an invalid hypothesis. The inability to refute a hypothesis does not mean the hypothesis is true.

Question 11

What is the final step in the scientific method?

Answer 11

Selecting the final hypothesis. Once the hypothesis has been tested, the investigator should review the entire process to ensure that all credible data are accounted for and all feasible alternate hypotheses have been considered and eliminated. The investigator should document the facts that support the final hypothesis to the exclusion of all other reasonable hypotheses.

Question 12

What is expectation bias?

Answer 12

A phenomenon that occurs when investigators reach a particular conclusion based on expectations without having examined or considered all of the relevant data. The investigator uses premature determination to influence analysis and investigative processes, including suggestive questioning of witnesses, leading to unscientific conclusions and misinterpretation or discarding of data that does not support the previously formed conclusion.

Question 13

What is confirmation bias?

Answer 13

Occurs when the investigator relies on data that supports the hypothesis and fails to look for, ignores, or dismisses contradictory or non-supporting data. The same data may support alternate and even opposing hypotheses. The failure to consider alternate hypotheses can result in incorrect conclusions.

Question 14

How does the scientific method prevent confirmation bias?

Answer 14

When using the scientific method, testing of hypotheses should be designed to disprove a hypothesis (falsification of the hypothesis) rather than relying only on confirming data that support the hypothesis. Working to disprove a hypothesis is an attempt to find all the data or reasons why the hypothesis is not supported or true.

Question 15

What is the rule about avoiding presumption?

Answer 15

No specific hypothesis can be reasonably formed or tested until some data have been collected. All investigations of fire and explosion incidents should be approached by the investigator without presumption as to origin, ignition sequence, cause, fire spread, or responsibility for the incident. All hypotheses should be subject to rigorous testing through the scientific method.

Question 16

What are the 6 steps of the Basic Method of Fire Investigation?

Answer 16

1. Receiving the assignment
2. Preparing for the investigation
3. Conducting the investigation
4. Collecting and preserving data and evidence
5. Analyzing the incident
6. Conclusions (drawing final hypotheses)

Question 17

What should be accomplished when receiving the assignment?

Answer 17

The investigator should be notified or briefed and told what he or she is to accomplish. Examples include: determine if fire is accidental or incendiary, determine origin/cause/responsibility, produce a written or oral report, prepare for criminal or civil litigation, make suggestions for code enforcement or changes, or make suggestions to manufacturers, industry associations, or government agencies.

Question 18

Why is preparing for the investigation important?

Answer 18

Preparation at this stage can greatly increase the efficiency and therefore the chances for success of the overall investigation. Estimating what tools, equipment, and personnel (both laborers and experts) will be needed can make the initial scene investigation, as well as subsequent investigative examinations and analyses, go more smoothly and be more productive.

Question 19

What is the fundamental purpose of conducting the investigation?

Answer 19

To collect all of the available data and document the incident scene. The investigator should conduct an examination of the scene if it is available and collect data necessary to the analysis.

Question 20

What tasks may be included in the investigation procedures?

Answer 20

Scene inspection or review of previous scene documentation done by others; scene documentation through photography and diagrams; evidence recognition, documentation, and preservation; witness interviews; review and analysis of the investigations of others; and identification and collection of data from other appropriate sources.

Question 21

Why is independent scene examination important?

Answer 21

In any incident scene investigation, it is necessary for at least one individual/organization to conduct an examination of the incident scene for the purpose of data collection and documentation. While it is preferable that all subsequent investigators have the opportunity to conduct an independent examination of the incident scene, in practice, not every scene is available at the time of every assignment.

Question 22

Can previously collected data be used successfully?

Answer 22

Yes. The lack of previously collected data from a properly documented scene can be used successfully in an analysis of the incident to reach valid conclusions through the appropriate use of the scientific method. Thus, the reliance on previously collected data and scene documentation should not be inherently considered a limitation in the ability to successfully investigate the incident.

Question 23

What is the goal of all investigators regarding scene documentation?

Answer 23

To arrive at accurate determinations related to the origin, cause, fire spread, and responsibility for the incident. Improper scene documentation can impair the opportunity of other interested parties to obtain the same evidentiary value from the data. This potential impairment underscores the importance of performing comprehensive scene documentation and data collection.

Question 24

What should be analyzed in Step 5 of the basic method?

Answer 24

All collected and available data should be analyzed using the principles of the scientific method. Depending on the nature and scope of one’s assignment, hypotheses should be developed and tested explaining the origin, ignition sequence, fire spread, fire cause or causes of damage or casualties, or responsibility for the incident.

Question 25

What are conclusions in fire investigation?

Answer 25

Conclusions, which are final hypotheses, are drawn as a result of testing the hypotheses. Conclusions should be drawn according to the principles expressed in this guide and reported appropriately.

Question 26

What are the two common expressions of certainty?

Answer 26

1. PROBABLE: This expression corresponds to being more likely true than not (greater than 50% confidence). 2. POSSIBLE: The hypothesis may be demonstrated to be feasible but cannot be either ruled out or declared probable. If two or more hypotheses are equally likely, then the expression must be 'possible'.

Question 27

When does an opinion qualify as an expert opinion?

Answer 27

If the level of certainty of an opinion is merely 'suspected,' the opinion does not qualify as an expert opinion. If the level of certainty is only 'possible,' the opinion should be specifically expressed as 'possible.' Only when the level of certainty is considered 'probable' should an opinion be expressed with reasonable certainty.

Question 28

What is reasonable fire investigation certainty?

Answer 28

Fire investigators achieve reasonable fire investigation certainty when they have properly applied all of the steps of the scientific method to reach a unique and reliable final hypothesis.

Question 29

What transparency requirements exist for expert opinions?

Answer 29

Where experts express their opinions in reports or testimony, they need to articulate how they applied the scientific method and effectively communicate their hypothesis, development and reasoning. Experts should disclose the data collected and utilized, including disclosing limitations if known. If an expert report is required, it should be complete and comprehensive.

Question 30

What is an administrative review?

Answer 30

An administrative review is one typically carried out within an organization to ensure that the investigator's work product meets the organization's quality assurance requirements. An administrative review will determine whether all of the steps outlined in an organization's procedures manual are required by agency policy, have been followed, and whether all of the appropriate documentation is present in the file, and may check for typographical or grammatical errors.

Question 31

What are the limitations of administrative reviews?

Answer 31

An administrative reviewer may not necessarily possess all of the knowledge, skills, and abilities of the investigator or of a technical reviewer. As such, the administrative reviewer may not be able to provide a substantive critique of the investigator's work product.

Question 32

What is a comprehensive technical review?

Answer 32

If a technical reviewer has been asked to critique all aspects of the investigator's work product, then the technical reviewer should be qualified and familiar with all aspects of proper fire investigation and should, at a minimum, have access to all of the documentation available to the investigator whose work is being reviewed.

Question 33

What is a specific aspect technical review?

Answer 33

If a technical reviewer has been asked to critique only specific aspects of the investigator's work product, then the technical reviewer should be qualified and familiar with those specific aspects and, at a minimum, have access to all documentation relevant to those aspects. A technical review can serve as an additional test of the various aspects of the investigator's work product.

Question 34

What are the limitations of technical reviews?

Answer 34

While a technical review may add significant value to an investigation, technical reviewers may be perceived as having an interest in the outcome of the review. Confirmation bias (attempting to confirm a hypothesis rather than attempting to disprove it) is a subset of expectation bias. This kind of bias can be introduced in the context of working relationships or friendships. Investigators who are asked to review a colleague's findings should strive to maintain a level of professional detachment.

Question 35

What is peer review?

Answer 35

Peer review is a formal procedure generally employed in prepublication review of scientific or technical documents and screening of grant applications by research-sponsoring agencies. Peer review carries with it a connotation of both independence and objectivity. Peer reviewers should not have any interest in the outcome of the review, and reviews are often conducted anonymously.

Question 36

What is NFPA 921?

Answer 36

NFPA 921 is a peer-reviewed document describing the methodologies and science associated with proper fire and explosion investigations. The methodologies used and the fire science relied on by an investigator are subject to peer review, with NFPA 921 being an example of such peer-reviewed standards.

Question 37

What are the limitations of peer reviews?

Answer 37

Peer reviewers should have the expertise to detect logic flaws and inappropriate applications of methodology or scientific principles, but because they generally have no basis to question an investigator's data, they are unlikely to be able to detect factual errors or incorrectly reported data. Conclusions based on incorrect data are likely to be incorrect themselves. Because of these limitations, a proper technical review will provide the best means to adequately assess the validity of the investigation's results.

Question 38

What should happen if a hypothesis cannot be conclusively determined?

Answer 38

If no hypothesis can be determined to be uniquely consistent with the facts and the principles of science, the issue should be considered undetermined.

Question 39

What is the critical question when selecting a final hypothesis?

Answer 39

'Are there any other hypotheses that are consistent with the data?' The investigator should document the facts that support the final hypothesis to the exclusion of all other reasonable hypotheses. When using the scientific method, the failure to consider alternate hypotheses is a serious error.

Question 40

What are the key legal requirements for expert opinions?

Answer 40

Investigators should understand that there are various legal requirements for the admissibility of expert opinions in different jurisdictions. For example, some courts have set a threshold of certainty for the investigator to be able to render opinions in court. The substantive content of expert reports or testimony should comply with any legal rules imposed in the jurisdiction in which they are provided.

Question 41

What is the purpose of the reporting procedure?

Answer 41

The reporting procedure may take many written or oral forms, depending on the specific responsibility of the investigator. Pertinent information should be reported in a proper form and forum to help prevent recurrence.