Activity-Level Proposition
Definition
A proposition about what happened. Example: 'The suspect handled the knife' versus 'The suspect never handled the knife.' Activity-level propositions require the scientist to incorporate assumptions about transfer, persistence, and background rates, making them more complex but more directly relevant to the legal issue.
Related terms
- Prosecutor's Fallacy
- The error of treating the RMP (or its reciprocal) as the probability that the defendant is innocent, or as the probability that...
- Daubert Standard
- The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...
- Defender's Fallacy
- Dismissing match evidence by citing the large absolute number of people who share the characteristic, ignoring all other evidence that narrows the...
- Frye Standard
- The US legal test for admissibility of scientific evidence, originating from Frye v. United States (1923), which required that a technique be...
- Likelihood Ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- Offence-Level Proposition
- A proposition about guilt. Example: 'The suspect committed the assault' versus 'The suspect did not commit the assault.' Forensic scientists must not...
- Source Attribution
- The inferential step of linking a trace to its donor. Serology identifies blood as human and potentially as a specific genetic type;...
- Source-Level Proposition
- A proposition about the origin of material. Example: 'The DNA profile originated from the suspect' versus 'The DNA profile originated from an...
- Verbal Equivalent Scale
- A standardised mapping from LR ranges to descriptive phrases, such as the ENFSI scale: LR 10 to 100 corresponds to 'moderate support',...
Explained in these topics
- Serology Evidence in Court: Interpretation and TestimonyA proposition addressing how biological material came to be at a location, such as whether the suspect physically handled an object, as opposed to a source-lev...
- Writing Evaluative Statements in Forensic ReportsA proposition about what happened. Example: 'The suspect handled the knife' versus 'The suspect never handled the knife.' Activity-level propositions require t...