Bias Flashcards
What is the connection between CAI and bias?
- importance of a transparent and logical process in both assessment and interpretation
- forensic science is context dependent but information conveyed incorrectly may bias opinion
- CAI requires choices to be made and unless conducted correctly these may introduce bias
What are the four key requirements to act with in the Forensic Science Regulator’s Codes of Practice and Conduct for Forensic Science Providers and Practitioners?
- honesty
- integrity
- objectivity
- impartiality
What are the three categories of cognitive bias?
- expectation
- confirmation
- anchoring effects or focalism
What is expectation bias?
- also known as experimenter’s bias
- where the expectation of what an individual will find affects what is actually found
What is confirmation bias?
- whereby people test hypotheses by looking for confirming evidence rather than for potentially conflicting evidence
What is anchoring effects or focalism?
occurs when an individual relies too heavily on an intial piece of information when making subsequent judgements, which are then interpreted on the basis of the anchor
What are three forms of bais’s?
- overconfidence - too confident and you take greater risks
- recency - the tendency to weigh the latest information more heavily than older data
- salience - our tendency to focus on the most easily recognisable features of the situation or concept
What is anchoring bias?
being over reliant on the first piece of information they hear
What is availability heuristic?
people who overestimate the importance of information that is available to them
What is the bandwagon effect?
the probability of one person adopting a belief increases based on the number of people who hold that belief
What is blind spot bias?
failing to recognise your own cognitive biases is a bias in itself
What is choice supportive bias?
when one chooses something which we tend to feel positive about
What is clustering illusion?
the tendency to see patterns in random events
What is confirmation bias?
when we tend to listen only to information that confirms our preconceptions
What is conservativism bias?
where people favour prior evidence over new evidence or information that has emerged
What is information bias?
the tendency to seek information when it does not affect action
What is the ostrich effect?
the decision to ignore a dangerous or negative information by buring one’s head in the sand
What is outcome bias?
judging decisions are based on the outcome rather than how exactly the decision was made
What is selective perception?
allowing our expectations to influence how we perceive events
What is survivorship bias?
an error that comes from focusing only on surviving examples causing us to misjudge a situation
What does the Criminal Procedure Rules say about an experts duty to the court?
- an expert must help the court to achieve the overriding objecting by giving an opinion that is objective and unbiased and within the experts area of expertise
- this duty overrides any obligation to the person from whom the expert receives instructions or by whom the expert is paid
What is the role of the forensic expert?
- to evaluate findings and results in the context of relevant circumstances
- the opinion should be balanced, robust, logical and transparent
What is contextual bias?
where someone has other information aside from that being considered which influences (either consciously or subconsciously) the outcome of the consideration
What are role effects?
- where scientists identify themselves within adversarial judicial systems as part of either the prosecution or defence teams
- this may introduce subconscious bias that can influence decisions
What is motivational bias?
- occurs where motivational influence on decision makiing, results in information consistent with a favoured conclusion tending to be subject to a lower level of scrutiny than information that may support a less favoured outcome
What are reconstructive effects?
- occur when people rely on memory rather than taking contemporaneous notes
- people tend to fill in gaps with what they believe should have happened
- may be influenced by protocol requirements when recalling events
When are the risks of bias lower?
- when results are clear and unambigious
- a methodical approach with defined standards build on principles that have ben tested and validated
- practitioners are well trained, experienced and continuously meet acceptable standards
- full independent reinterpretation is done
When are the risks of bias greater?
- when the approach is unresearched and personal to the practitioner
- when results are complex, of poor quality and there is an increased reliance on subjective opinion
- practitioners are inexperienced, unmonitored and left to adopt their own approach
- checking is conducted collaboratively or not at all
What is debias?
the reduction or elimination of the impact of bias in decision making and problem solving
What is photogrammetry?
the practice of obtaining reliable information about physical objects through the processes of recording, measuring and interpretating photographic images
What is psychological contamination?
exposure to other information that is irrelevant to the assessment but that introduces sub consious bias into the findings
What are the threats to impartiality?
- being the sole reviewer
- being over-familiar
- having organisational and management structures that could be perceived to reward bias where a culter of performance measurment and time pressures could pressurise examiners into biasing decisions
How to make sure people are not susceptible to psychological and cognitive influences?
- proficiency-testing
- blind trials - can be time consuming tho
- undertake a mixed programme of declared and undeclared trials
How to avoid reconstructive effects?
- contemporaneous notes
- during collection and processing
What is a brief outline of forensic processes that a lab follows?
- define requirement
- develop examination strategy
- agree examination strategy with client
- carry out analyses
- review the quality and content of results
- compare results with references
- evaluate and interpret findings
- second expert verifies
- communicate findings
What are the ways to reduce the risk of cognitive bias in evaluative mode?
- go through a formal process of pre-assing the expected probabilities for a realistic range of outcomes in as many or as few categories as is sensible for the examination
- record their opinions
What type of bias does the LR decrease?
confirmation
What are the factors that police must take into consideration when attending a scene?
- preserving the scene
- securing evidence
- the speed of response
- the proportionate use of resources based on the seriousness of the crime
- all are overriden by the preservation of life tho
R v Pickering
- convicted for sexual assult on a girl under the age of 13
- none of the DNA results were suitable for statistical analysis as there must have been at least one other unknown person who contributed to the mixed profile
- no likelihood ratios were able to be made
- presence of amylase was strong supportive evidence for the Hp
Why has there been an increasing risk of cognitive contamination in DNA evidence?
- stochastic effects is increasing
- conditions in which subjective opinion tends to be relied on are more commonly encountered
Dlugosz case 2011
- convicted of burglary robber and manslaughter
- could not quantify the level of support from the DNA samples found on chisels because it was a mixed profile
- since then if you cannot statistically evaluate the DNA evidence it will be ruled inadmissible
- may have been prejudiced (biased) by his previous convictions
What are some mitigation strategies for DNA samples?
- prior interpretation of case sample result before reference result is revealed
- noting the suitability in include or exclude
- assessment of the number of contributors
- level of representation of contributors
- potential for stochastic effects
- identification of likely/unlikely genotype combinations that might explain the mixture
What is recommended for DNA profile interpretation in all circumstances?
- full checking - repeat interpretation by an experienced and competent colleague including prior interpretations of the case sample result before the reference
- the check should be conducted independent of and uninfluenced - use original unmodified hard copy or electronic results
How to make the correct selection of case stains/samples
- multiple analyses to asses stochastic effects in low template samples
- replication should be applied whenever a poor quality profile is to be relied on
*
What do you employ when there is no option for objective evaluation?
quantitative and subjective-based approaches
* validated
* demonstrates robustness of resultant conclusions and opinions
What were the findings from the scottish police services authority?
- improved note taking
- no prior knowledge or access to case-related information
- blind verification process
- removal of any context information or related communication documentation
- training programmes to explore cognitive bias
What does ACE-V stand for?
- analysis
- comparison
- evaluation
- verification
When is ACE-V used?
fingerprint comparison
What does ACE-V mean when analysing a print?
- A: is the mark of suffcient quality
- C: can we include or exclude
- E: identified or not
- V: the need for independent second checking
What three things can the risk of inherent in the fingerprint examination process be categorised as?
- contextual bias
- confirmation bias
- cultural bias
How is there contextural bias in fingerprints?
- nature and details of the crime (background info)
- association with or personal knowledge of victim
- status of person in custody
- previous criminal activity of suspects
- location of crime
- media or public interest
- personal morals
- time pressure
Where can there be confirmation bias in fingerprint evidence?
- police and prosecution hoping it will solve the crime
- a personal moral ode to do the right thing
- having prior knowledge of the previous examiners findings and conclusions
Where could there be cultural bias in fingerprint evidence?
- strict hierachical structures based on time served rather than competence
- over confidence in individual or organisation
- lack of interaction with peers or exposure to alternative methods of working
- lack of acceptance of the potential for errors or effective root cause analysis of errors
Where are some examples of cognitive risks from the scottish fingerprint enquiry?
Case studies
- Brandon Mayfield - resulted in a procedure review
- Shirley McKie
What cases do blind verifications take place?
- those with single mark conclusions
- circumstances where there are conflicts between examiners
- circumstances where there are conflicts on decisions of value or no value
What is a blind verification?
the independent application of ACE by another qualified examiner who does not know the conclusions of the primary examiner
What is the generic process for mark evidence?
- examine the mark
- use recovery and enhancement techniques as required
- generate the control item
- make test marks if required in the appropriate manner
- undertake a comparison using appropriate methods
- interpret and evaluate findings
- verify the results
- describe findings in a statement or report
- might have to go to court to give oral testimony
What is mark comparison like?
- human operator, no instrumental analysis
- methods are usually side by side comparisons or overlay
- subjective assessment
What are some mitigation strategies for mark evidence?
- CAI, comparison of expected, pre-assessed outcomes of appropriate hypotheses with actual results
- full disclosure of all data used in the evaluation
- blind checker
- critical findings checked by a second authorised examiner
- validation testing
- ongoing monitoring of the competence of practitioners using proficiency testing - quality checks
- training and education in bias
What is the general process for all trace evidence?
comparison of crime material with one or more known/reference samples
What are some mitigation strategies for trace evidence?
- independent checking - where only subjective observational assessments of a match are possible
- independent chekcing of analytical results
- use a statistical approach for evaluation
- CAI - robust and documented comparison of expected and pre-assessed outcomes with actual results under appropriate competing hypotheses
- training
- quality assurance trials
What are the 5 levels of taxonomy for linear sequential unmasking?
- the trace evidence
- reference materials
- case information - managed by case managers
- base rate expectations that arise from their experience
- organisational and cultural factors
How can reference samples cause bias?
analysts interpretation could be influenced by knowing the characteristics of the reference sample
What is linear sequential unmasking?
working from the evidence to the suspect rather than from the suspect to the evidence
* does not prevent exposure to biasing relevant info
* does manate that this info is presented as late as possible in the examination process and only when it is necessary
* first examine and document the trace evidence from the crime scene (level 1) before being exposed to the reference material (level 2)
What factors effect decision making unconsciously?
- case evidence
- reference materials
- irrelevant case info
- base rate expectations
- organisational factors
- training and motivation
- cognitive architecture and the brain
What is expected frequency bias?
being accustomed to a particular result occuring at a certain rate and then expecting it to keep occuring at the same rate
In summary what are ways to mitigate bias in forensic investigation?
- removing irrelevant contextual info from samples prior to running tests - case management
- minimising bias in expected outcomes - blind verification
Introduced to prevent contextual bias by protecting examiners from task irrelevant information?
Case managers
Synonymous with base rate, a factor that makes unconsiously effect decision-making
background rate
Where the DNA scientist is required to make their own supposition about the appropriate defence hypothesis?
Proxy proposition
Refers to a property of being well described by random probability distribution?
Stochastic
What type of bias is referring to subconscious influence of prior beliefs?
Cognitive
Type of bias associated with extraneous information, influencing forensic judgement
Contextual
When we allow the anticipated results to influence our interpretation of the evidence
Expectation bias
What are some cultural influences that can impact the decision-making process from the Scottish Fingerprint Enquiry?
- over confidence
- lack of exposure to alternative methods
- lack of acceptance of the potential errors or effective root cause analysis of errors
What was the case of Shirely McKie 1999?
- she was an investigating officer for a murder
- it was said that her fingerprint was found
- misidentification of fingerprint
What was the case of Brandon Mayfield 2006?
- misidentification of fingerprint
- ignored critical differences in the prints
- due to the unusual level of similarity, they were less focused on information which might exonerate Mayfield
- FBI introduced a system of blind verification due to this
