Case Assessment and Interpretation Flashcards
What are the objectivies of the CAI model?
- improve decision making and resource allocation
- improve relationships and develop partnerships
- provide value (defined by client agency)
- service the needs of the Criminal Justice System
What does the assessment part of CAI mean?
How we manage, prioritise and triage the demand
What does the interpretation part of CAI mean?
How we report results in a logical and quantitative way
What is the first phase of the CAI model?
- customer requirment
- case information
- customer needs
What is the second phase of the CAI model?
- case pre-assessment
- determine forensic strategy
- identify propositions
What is the third and final stage of the CAI model?
- service delivery
- forensic examination
- evaluate outcomes
- interpretation and report
What are the three hierarchy of propositions?
- source (has the semen originated from the suspect?)
- activity (has the suspect had sexual intercourse with the complainant?)
- offence (did the suspect rape the complainant?)
What proposition is this: the blood on Mr C’s clothing came from Mr Z
Source (level 1)
What level of proposition is this: the glass fragments came from window X
Source (level 1)
What level of proposition is that: Mr A commited the burglary
Offence (level 3)
What level of proposition is this: Mr A was not present when the window was smashed
Activity (level 2)
What framework does the CAI model provide to the investigator?
5 points
- ensures requirements are clearly articulated
- assists in setting forensic examination strategy
- assists decision making
- provides staged information
- enhances value
What framework does the CAI model provide to the CJS?
4 points
- ensures a balanced unbaised approach
- ensures impartiality and transparency
- allows discussion of strength of evidence
- adds value
What does CAI require?
- communication between all key parties
- clear understanding of each others requirements
- agreement of forensic examination strategy
- understanding of expected outcomes
- exploration of staged apprach where possible
How do you work out the posterior odds?
likelihood ratio * prior odds
What framework does the CAI model provide to forensic scientists?
6 points
- ensures understanding of case information and issues
- leads to an agreed forensic examination strategy
- defines proposition for testing
- enables staged examination and reporting
- underpinned by sound statistical theory
- adds value to the scientists role
What is the likelihood ratio?
Probability of the evidence given the prosecution hypothesis and information divided by the probability of the evidence given the defence hypothesis and the information
What is conditional probability?
the likelihood of an event occuring given that another event has already occurred
What is independent odds?
The likelihood of two events occurring independently of each other
* the occurrence of one event does not affect the probability of the other event occurring
What was the case of Sir Roy Meadow?
He used conditional odds to work out the likelihood of another infant death when he should have used independent odds
What do the values of the likelihood ratio indicate?
1< = supports the prosecution hypothesis
1 = neutral
<1 = supports the defence hypothesis
What is the prosecutors fallacy?
When the prosecutor incorrectly interprets the probability of evidence given the defendants guilt as the probability of guilt given the evidence