Human Reliability Flashcards
(71 cards)
1
Q
Definition of Human Reliability
A
Capacity of Humans to complete a task under given conditions within defined time and defined acceptance limits
2
Q
Definition of Reliability Paramaters (theoretical, priori)
A
Characterizes the probability distributoin of a relability feature
3
Q
Definition of Reliability Characteristics (empirical, posteriori
A
Characterize the Frequency distribution of a reliability feature
4
Q
Definition of Availability Measure
A
Time in which the machine is available for work:
V = MTBF/(MTBF + MTTR)
MTBF = Mean time between Failures
MTTR = Mean time to Repair
5
Q
Definition of Residual Risk
A
The Risk remaining after implementation of safety measures.
6
Q
Passive vs Active Safety
A
Passive = Reducing the probability of damage after ocurrence of unwanted event (Seat belts)
Active = Reducing probability of an unwanted event happening (Autonomous Emergency Breaking)
7
Q
Risk Equation
A
Risk = Probability x Severity
8
Q
Human Error Probability Equation
A
HEP = N. of Errors Observed (n) / N. of Possibilities for an Error (N)
9
Q
Binomial vs Poisson vs Weibull Distribution
A
Binomial = Finite number of samples
Poisson = Infinite Samples (Or very very large number of samples)
Weibull = Mostly useful to calculate lifespan, durability (Involves Time)
10
Q
Calculating Probability with Binomial Distribution (Equation)
A
P(X = k) = (nk)(p)k(q)n-k
Where p = error probability
q = 1-p
11
Q
Calculating Probability with Poisson Distribution
A
P(X = k) = ((n p)k/k!) e-np
where n x p is the expected value (µ) so:
P(X = k) = ((µ)k/k!) e-µ
11
Q
Calculating Lifespan (failure) with Weibull Distribution
A
F(t) = 1 - e-(t/T)b
where T = time to which 63.2% of components have failed
b = shape parameter
F(t) = probability that the lifespan is at most equal to t
12
Q
Survival Probability (Equation)
A
R(t) = 1- F(t)
1 - Failure probability at certain time
13
Q
Bayes Theorem if Dependence is Assumed (equation):
A
P(A Ո B) = P(A|B)P(B) = P(B|A)P(A)
P(A|B) = P(B|A)P(A) / P(B)
P(A Ո B) = Probability that both A and B are True
14
Q
Law of Total Probability (equation) P(B)
A
P(B) = P(B|A)P(A) + P(B|A-)P(A-)
15
Q
Bayes Theorem (Equation)
A
P(A|B) = (P(B|A)P(A))/(P(B|A)P(A)+P(B|A-)P(A-))
Probability of A ocurring given that B is true
16
Q
The probability of A and B being true is:
A
P(A and B) = P(A) x P(B)
17
Q
Probability of A or B or both being true
A
P(A or B) = 1-[ (1-P(A)) x (1-P(B)) ]
Only applies if A and B are independent
18
Q
Probability of either A or B (XOR)
A
P(A “or” B) = P(A) + P(B)
either A or B (NOT Both)
19
Q
How is High Quality Ergonomics Achieved?
A
By:
-Use of a system-approach
-Design-based approach
-Equal performance in: performance and well-being.
20
Q
What is the main approach for the analysis of human factors?
A
Organization, Machine, and Humans as separate entities but working with eachother.
21
Q
Calculate Work Quality
A
Result/Task
22
Q
Calculate work Performance
A
Work Quality/Time
23
Q
What is “Working Task”?
A
What is requested to the operators. To do a task under given conditions and procedures to achieve a working result.
24
What is "Work Load"?
All external conditions/requirements in the working system that could influence a person.
25
What is "Working Stress"?
The effect of the Work Load on a person relative to his/her individual characteristics.
26
What is "Quality of Work"?
How much the working result matches the working task
27
What is the "Acceptance Area"?
Limits which define quality of work in accordance to requirements.
28
What is "Dependability"?
Measure of a systems availability, reliability, maintainability and even maintenance support performance.
29
Difference between Reliability "Parameters" and "Characteristics"?
Reliability Parameters: Theoretical, Priori. Characterizes the probability distribution of a reliability feature.
Reliability Characteristics: Empirical, posteriori.
Characterizes frequency distribution of reliability feature.
30
Definition of "Safety"
Measure of the Absence of Danger.
31
Definition of "Risk"
Frequency or probability of a defined event resulting into damage.
Risk = Probability * Severity
32
How is the Human Reliability Parameter (HRP) calculated?
HRP = 1-HEP
33
How do many technical systems/products etc. Failure Rate vs. Life time look?
Like a Bathtub.
In the first curve downwards, early failures are produced. These are mainly due to manufacturing errors.
The sector of straight line random errors are produced. These are mainly attributed to maintenance failures
34
What is "Conditional Probability"?
When the probability of A increases when B has occurred. Dependency between failures.
35
How are stress levels divided?
-Measurable Quantities: Radiation, heat, etc.
-Non-measurable Stress Factors: Time Pressure, Sociological Factors, etc.
36
How do humans process information?
1.- Perception: Optical, Acoustical, Vestibular, Haptic, Thermal, Taste.
2.-Processing: Knowledge based, Rule based, Skill based.
3.- Transition: Upper extremities, Lower extremities, Language.
37
What are some examples of human error in the 3 steps to human information processing?
1.-Perception: Overlooking information, Lack of Perception.
2.-Processing: Forgot, Education deficiencies, Ignorance, Lack of Experience.
3.-Transition: Confusion, Lack of practice.
38
What are the 3 types of tolerance limits?
-Fixed (Physical/Mechanical)
-Empirical (Exceedence cannot be directly observed)
-Conventional (Legal)
39
What are some differences between Occurrence and Cause Based Classification of Errors?
-Occurrence Based (phenomenological): Errors according to behavior/psychological point of view. What? How? Who? When?
-Cause Based (causal): Investigation of cause of error, the origin. Why?
40
What are Performance Shaping Factors?
PSFs: Factors that influence human ability to reliably perform a task.
41
How are PSFs divided and subdivided?
-External: Organizational (Structure and Dynamics) and Technical Prerequisites (Task difficulty, Situational Factors)
-Internal: Capacity (Physiological and Psychological), Readiness (Physiological, Psychological).
42
What are the 3 types of behaviors that are looked at in cause-based classification? What are some differences between them?
-Skill-based: Automatic reaction to signals, Little interpretation needed, Low demand for attention resources, Exremely high user expertise is needed. Most errors are execution errors due to misdirected attention or interruptions. (<200ms needed)
-Rule-based: Automatic reaction to meaningful information, User is familiar with task, "If-Then" behavior patterns, Binding of attention resources. Most errors are a combination of execution and planning errors due to misinterpretations, or wrong rules. (seconds...minutes needed)
-Knowledge-based: Analytical procedure in new situations, "Problem Solving", High Cognitive Effort. Errors are mostly Planning errors due to limited resources, memory, or biases in hypothesis. (minutes...hours needed)
43
What are the 2 types of safety?
Safety I: As few things as possible go wrong. The system can be decomposed, each element is bimodal, each element can be analyzed individually, the order of events is fixed. Direct relations (Function = Success, Malfunction = Failure)
Safety II: As many things as possible go right. The system cannot be decomposed, Performance is always variable, Functions must be flexible to fit conditions. Relations are variable (Everyday Work = Success, but also Everyday Work = Failure).
44
What are Gen 1 Safety Methods?
"Sequential Methods":
Focus on accidents caused by malfunctions and Human Error, Cause-Effect relationship is linear and deterministic, No Feedback loops. E.G. Domino Theory, THERP, SAINT, ESAT, SLIM, PTD, etc.
45
What are Gen 2 Safety Methods?
"Epidemiological Methods":
Focus changing from human factors to organization, Accidents are combinations of different factors, Understanding of accidents in complex systems, thinking at different Hirearchy levels. Swiss Cheese Model, CREAM, etc.
46
What is the THERP Method?
Technique for Human Error Rate Prediction. A sequential method (Gen 1) suitable for the analysis of highly practiced activities.
-In-depth task decomposition
-Plausible results with competent application.
-Speculative for knowledge-based behavior in an interruption.
47
What are the steps to implement THERP?
1.- Definition of the errors of interest for the analysis.
2.- Task analysis: Identify possible mistakes, quantitative consideration of human factors.
3.- Estimate influence of human error on system reliability.
4.- Recommendations for change. (Iterations from step 2 to 4)
48
What is the HEART Method?
Human Error Assessment and Reduction Technique (Gen 2). Epidemiological method designed for holistically defined tasks (e.g. put system x into operation) rather tan elementary tasks (push x button).
-PSF related HEP qualification.
-Reliable reference of HEP required.
-PSFs are known and assessable.
49
What are the main differences between THERP and HEART?
THERP: Primarily Detailed Evaluation, Complex task analysis and quantification, Detailed identification of flaws and relative statements about possible weaknesses.
HEART: Primarily time-saving preliminary estimation (screening), PSF-related quantification, Identification of weak points possible.
50
What are similarities and differences between THERP, SAINT and ESAT?
Similar: Procedure, Overall probability calculation.
Different: SAINT uses Time Factor as a continuous simulation parameter, while THERP and ESAT use it as factor for PSFs
51
What is the SLIM Method?
Subjective Likelihood Index Methodology. (Gen 1). Subjective evaluation of Human Reliability depending on specific PSFs, such as motivation, working conditions, etc.
52
How is a PTD used?
PTD (Probability Tree Diagram). It is used to calculate individual failure probabilities, by multiplying probabilities of steps in a sequence/process, and adding when there are more than 1 route to get to the specific failure.
53
What is the HFAC procedure?
Human Factors Analysis Classification System. (Gen 2). A more developed Swiss Cheese Model for more accurate accident analysis.
54
What is the FRAM method?
Functional Resonance Analysis Method. Its a method used to identify how a system functions for everyday work to go well, by understanding the variability and how these have an effect on the function.
-Equivalence of failures and successes
-Causes are reconstructed NOT found.
-Approximate Adjustments.
-Functional Resonance
55
What are the basic steps to implement FRAM?
1.- Identify system functions: Input, Output, Precondition, Resource, Control, TIme, for each process segment.
2.-Identification of Performance Variability: Sources and Phenotypes.
3.- Aggregation of Variability: In the stream of functions, variability has an effect on downstream variability.
3.- Management of Variability: Augment Positive Effects, Dampen Negative Effects, Solutions are to be found and indicators established.
56
Classification of Errors by RIgby?
-Sporadic errors: single events. Safety mechanisms can be used.
-Random errors: Frequent events with no tendency/pattern. General Training measures (not very effective)
-Systematic errors: Events with clear visible trend. Well addressed through targeted training.
57
Classification of Errors by Meister?
-Faulty execution of required action.
-Failure to perform required action.
-Performing an action outside required sequence.
-Performing unnecessary/inadmissible action.
58
Classification of Errors by Swain and Guttman?
This approach takes into account PSFs.
-Error of Commission: selection, sequence, time, quality.
-Error of Omission: Entire Task, step in Task.
59
Classification of Errors using GEMS by Reason?
Generic Error Modeling System.
-Skill-Based: errors of attention.
-Rule-Based: Application of incorrect rule. Errors due to incorrect pattern matching, Misconstructed view of state.
-Knowledge-Based: Incorrect understanding of system, overconfidence, cognitive strain.
60
What is the Haddon Matrix?
It is a framework used in injury prevention that categorizes the causes of injury in 3 phases: pre-event (Prevention), event (Minimize damage), post-event (Treatment)
61
System Approaches to prevent failure?
-Forcing Function (Usually a Physical Barrier)
-Fail-Safe Systems (In case of error, system is transferred to a safe state)
-Fault Tolerance (Tolerance of errors and variability)
-Redundancy (Parallel design of a system)
-Automation (System which does not depend completely on a human)
62
What are the Basic Measures in Human Reliability?
-Improvement of the Work System (external PSFs): Better design of physical environment.
-Restoration and Maintenance of Human Performance and Motivation (internal PSFs): Better Corporate Culture, Work Organization, Training
63
Basic Principles of System Ergonomics?
-Function
-Feedback
-Compatibility
64
What is Safety Culture?
The way safety is perceived, valued and prioritized in an organization.
65
How is Safety Culture divided?
-Reporting Culture (share information about potential hazards)
-Just Culture (Accountability, rewarding)
-Flexible Culture (Effective Adaptation to changing demands)
-Learning Culture (Willingness to change based on assessments, audits, etc.)
-Informed Culture (Combining different information including incidents to integrate a safety system)
66
What is standardization?
The process of implementing and developing technical standards based on consensus of different parties.
67
What are some important institutes in standardization in Germany?
DIN : Deutsches Institut für Normung
VDI: Verein Deutscher Ingenieure
VDE: Verband der Elektrotechnik Elektronik und Informationstechnik.
68
What are some European institutes in standardization?
CEN: European Committee for Standardization.
ETSI: European Telecommunications Standards Institute.
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What are some International Standardization Institutes?
ISO: International Organization for Standardization.
IEEE: Institute of Electrical and Electronics Engineers.
70
What are some examples of Human Reliability Standards?
VDI 4006 Part 1: Ergonomic requirements and methods of evaluation (HEP, PSFs, Human-Task-System Interaction)
VDI 4006 Part 2 and 3: Methods of Quantitative assessment of Human Reliability and Methods of Event Analysis.
ISO 9241: Ergonomic Requiremens, Processes for Design, etc.
