Base Rate
Definition
The prior probability of an event or proposition before specific evidence is considered. In forensic inference, the base rate is the probability that the proposition of interest (for example, that a particular suspect is the source of a trace) is true in the absence of the forensic evidence being evaluated.
Related terms
- AUC Statistic
- Area under the receiver operating characteristic curve; the standard criterion-validity metric for forensic risk and malingering instruments, with 0.70 considered a minimum...
- Bonferroni Correction
- A standard adjustment for multiple comparisons: the significance threshold for any individual test is divided by the total number of tests performed,...
- BSA 2023 § 39
- Section 39 of the Bharatiya Sakshya Adhiniyam 2023, the provision governing expert opinion evidence in Indian courts. Replaced Indian Evidence Act 1872...
- Consequential Validity
- The fairness and equity implications of test use; includes disparate impact on racial or cultural groups and the systematic bias this may...
- Criterion Validity
- The degree to which test scores predict or correlate with an external criterion; predictive criterion validity is most relevant to forensic instruments.
- Database Match Probability
- The adjusted probability that a coincidental match to a crime-scene profile exists somewhere in a database, accounting for the number of profiles...
- Daubert Standard
- The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...
- Ecological Fallacy
- The error of applying a statistical association observed at the population or group level to an individual, without verifying that the individual...
- Ecological Validity
- The degree to which a measurement or test procedure produces results that generalise from the controlled laboratory context to the real-world condition...
- Incremental Validity
- The improvement in predictive accuracy that a test adds over and above prior information; justifies the cost and burden of additional assessment.
- Look-Elsewhere Effect
- The inflated apparent significance of a finding that arises when many features, tests, or subsets are examined and only the significant result...
- Multiple Comparisons Problem
- The inflation of the probability of at least one false-positive result that occurs when many statistical tests or pairwise comparisons are made....
Explained in these topics
- Foundations of Forensic Assessment and Test ValidityThe prevalence of the condition of interest in the relevant population; critical for calculating positive and negative predictive values from sensitivity and s...
- Other Statistical Fallacies in Forensic ContextsThe prior probability of an event or proposition before specific evidence is considered. In forensic inference, the base rate is the probability that the propo...