Population Frequency Database
Definition
The reference dataset from which the denominator of a fingerprint likelihood ratio is estimated: the frequency with which a given configuration of minutiae features appears in a large sample of fingers drawn from the relevant population. The size and representativeness of this database is the primary statistical criticism of FRStat.
- Function
- Denominator for a fingerprint likelihood ratio
- Related system
- FRStat
- Main criticism
- Database size and representativeness
Common questions
Why is the database's representativeness criticised?+
If the sampled fingers do not reflect the relevant population's true range of minutiae configurations, the estimated frequency of a given configuration can be too high or too low, which distorts the resulting likelihood ratio.
How does this connect to the post-2009 NAS debate?+
The 2009 National Academy of Sciences report questioned whether fingerprint conclusions had an adequate statistical foundation, and FRStat's population database is the part of the method most directly targeted by that criticism.
Related terms
- 2009 NAS Report
- The National Academy of Sciences report Strengthening Forensic Science in the United States, which found that fingerprint individualization claims lacked empirical population-frequency...
- Categorical Identification
- The historical fingerprint testimony model in which the examiner declares that the latent print originated from the named person to the exclusion...
- ENFSI Evaluative Reporting Framework
- The ENFSI Guideline for Evaluative Reporting in Forensic Science (2015), which specifies that forensic identification opinions should be expressed as likelihood ratios...
- FRStat
- The fingerprint statistical scoring model developed by the FBI Laboratory and Iowa State University (Professor Alicia Carriquiry). Takes ACE-V comparison documentation as...
- 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...
- NIST ELFT-EFS (2012)
- The NIST Evaluation of Latent Fingerprint Technologies: Extended Feature Sets, a large-scale evaluation of both automated AFIS algorithms and human examiner performance....
- R V. T (2010)
- UK Court of Appeal decision on footwear evidence likelihood ratios that expressed caution about numerical LR presentation where the underlying database was...
- Ulery Et Al. 2011
- The FBI black-box study that tested 169 fingerprint examiners on 744 latent-exemplar pairs, finding a false-positive rate of 0.1%. The study empirically...
- Verbal Scale
- The ENFSI translation of numerical likelihood ratios into courtroom language: very strong support (LR over 10,000), strong support (LR 1,000-10,000), moderate support...