ForensicSpot10 modules
Forensic Statistics
The statistics of evidence evaluation: probability, match probabilities, the likelihood ratio, Bayesian reasoning, fallacies, and how strength of evidence is reported.
- 60hours
- 30topics
- 10modules
Module 16 hrs3 topics
Why Statistics in Forensic Science
How numbers enter forensic conclusions and why courts increasingly demand them.
Start module- How Numbers Enter Forensic ConclusionsWhy forensic science moved from categorical claims to quantified evidential weight, and the pressures that made numerical reasoning a courtroom expectation.13 min
- The Role of Statistics in Evidence EvaluationWhere statistics enters forensic practice, comparison, classification, source attribution and evaluative reporting, and what it can and cannot contribute.13 min
- History of Statistical Evidence in CourtsLandmark cases like People v. Collins and R v. Sally Clark, where statistical arguments shaped or distorted verdicts, and the lessons for expert witnesses.13 min
Module 26 hrs3 topics
Probability Foundations
Probability rules, conditional probability, independence, and the meaning of "random match".
Start module- Basic Probability RulesThe axioms of probability, the addition and multiplication rules, and complementary events, explained through trace-evidence and database-search examples.13 min
- Conditional Probability and IndependenceWhat it means for one event to depend on another, why independence must be justified rather than assumed, and how wrong assumptions cause courtroom errors.13 min
- The Concept of Random Match ProbabilityThe random match probability is the chance an unrelated person would share the evidence, not the probability of innocence, a distinction courts often miss.13 min
Module 36 hrs3 topics
Describing Data
Descriptive statistics, variability, and presenting forensic data honestly.
Start module- Descriptive Statistics for Forensic DataMean, median, mode, variance and standard deviation applied to forensic measurements, with a warning against cherry-picking summary statistics.13 min
- Visualising Forensic DataHistograms, box plots, scatter plots and kernel density estimates for exploring forensic datasets, and how graphical choices can clarify or mislead.13 min
- Variability and Measurement ErrorNatural within-class and between-class variability differs from instrument measurement error, and both must be characterised before evidence can be interpreted.13 min
Module 46 hrs3 topics
Distributions and Sampling
Common distributions, sampling, confidence intervals, and what a sample can support.
Start module- Common Distributions in Forensic ScienceThe normal, binomial, Poisson and gamma distributions, where each arises in forensic data, and how the wrong distributional model skews inference.13 min
- Sampling Strategies and Representative DataRandom, stratified and cluster sampling, and why the quality of a conclusion depends on how the sample was drawn given limited exhibit material.13 min
- Confidence Intervals and What a Sample Can SupportHow confidence intervals are built and correctly read, since a 95% interval does not mean a 95% chance the true value lies inside it.13 min
Module 56 hrs3 topics
Match Probabilities
Random match probability, population databases, and the statistics behind a "match".
Start module- Population Databases for Forensic StatisticsHow reference population databases for DNA, fingerprint and glass match probabilities are built and validated, and what a mismatched population costs.13 min
- DNA Match Probability CalculationThe product rule for multi-locus DNA match probabilities and the NRC-II theta correction applied for population substructure.13 min
- Match Probabilities Beyond DNAHow match-probability reasoning extends to fingerprints, glass, fibres and footwear, and the challenge of validating rarity estimates without DNA-scale data.13 min
Module 66 hrs3 topics
The Likelihood Ratio Framework
The likelihood ratio as the logically correct way to weigh evidence, with worked cases.
Start module- The Likelihood Ratio: Definition and LogicThe likelihood ratio weighs the evidence under the prosecution and defence hypotheses, and why it, not the posterior probability of guilt, is the expert's job.13 min
- Computing Likelihood Ratios: Worked ExamplesWorked likelihood-ratio calculations for DNA, glass refractive index and speaker comparison show how values above and below 1 support opposing propositions.13 min
- Strength of Evidence and Likelihood Ratio ScalesNumerical scales like the Jeffreys scale describe evidential strength, and how they connect to the verbal equivalents used in evaluative reports.13 min
Module 76 hrs3 topics
Bayesian Evidence Evaluation
Prior and posterior odds, Bayes theorem in court, and the role of the fact-finder.
Start module- Bayes Theorem in Evidence EvaluationBayes theorem in odds form updates prior odds to posterior odds by the likelihood ratio, with the prior reserved for the fact-finder, not the expert.13 min
- Prior and Posterior Odds in CourtHow prior odds form from non-scientific case facts and shift toward posterior odds via the expert's likelihood ratio, dividing roles between scientist and jury.13 min
- Bayesian Networks for Complex EvidenceDirected acyclic graphs model dependencies among multiple evidence items without violating conditional-probability rules, applied to mixed DNA profiles.13 min
Module 86 hrs3 topics
Statistical Fallacies
The prosecutor fallacy, the defence fallacy, and the transposed conditional.
Start module- The Prosecutor's FallacyThe prosecutor's fallacy mistakes the probability of the evidence given innocence for the probability of innocence given the evidence.13 min
- The Defence FallacyThe defence fallacy dismisses a one-in-a-million match as negligible because millions could match, ignoring the rest of the case's evidence.13 min
- Other Statistical Fallacies in Forensic ContextsBase-rate neglect, the ecological fallacy, multiple comparisons in database searches and the look-elsewhere effect all distort probabilistic reasoning.13 min
Module 96 hrs3 topics
Evaluative Reporting
Verbal equivalents of the likelihood ratio, standards for evaluative opinions, and report language.
Start module- Verbal Equivalents of the Likelihood RatioVerbal scales from ENFSI, the UK Forensic Science Regulator and AFSP Australia map LR ranges to phrases like 'moderate support', with risks of misreading.13 min
- Evaluative Opinion Standards and FrameworksENFSI's Guideline for Evaluative Reporting, ILAC G19 and ISO 17025 govern what a compliant evaluative opinion must include and must not claim.13 min
- Writing Evaluative Statements in Forensic ReportsHow to draft propositions at the source, activity or offence level, pick the right verbal equivalent, and structure an evaluative report without common errors.13 min
Module 106 hrs3 topics
Error, Validation and Uncertainty
Error rates, method validation, measurement uncertainty, and proficiency testing.
Start module- False Positive and False Negative Error RatesFalse positive and false negative rates in forensic classification, how they trade off on the ROC curve, and why both must be estimated and disclosed.13 min
- Method Validation and Fitness for PurposeThe validation studies, limit of detection, selectivity, robustness and reproducibility, that a forensic method needs before operational use under ISO 17025.13 min
- Measurement Uncertainty and Proficiency TestingThe GUM framework for measurement uncertainty, how it propagates through forensic calculations, and how proficiency testing checks laboratory performance.13 min