Anaes Vivas · Measurement & monitoring physics
Data viva — the 2x2 contingency table and diagnostic test performance
A data viva on the 2x2 contingency table of diagnostic test performance — the orientation of the four cells (TP, FP, FN, TN); sensitivity and specificity read down the columns (prevalence-independent); PPV and NPV read across the rows (prevalence-dependent); the mnemonics SnNout and SpPin; likelihood ratios (LR+ equals sensitivity over 1 minus specificity, LR- equals 1 minus sensitivity over specificity) as the prevalence-independent way to move from pre-test to post-test probability via Bayes' theorem. Applied to the AI iridocorneal-angle classification study, the AI-CT study for MACE, and the regional-versus-general-anaesthesia meta-analysis.
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The figure shows a 2x2 contingency table. The columns are defined by the reference standard — disease present and disease absent. The rows are defined by the index test — test positive and test negative. The four cells are labelled, and four formulas are written beside the margins. Interpret the figure, naming each cell, stating what each formula measures, and explaining which quantities depend on prevalence and which do not.
References3ShowHide
- [1]Rubegni G, et al. Automated iridocorneal angle classification using a multimodal large language model. Graefes Arch Clin Exp Ophthalmol, 2026.PMID 42363984
- [5]Xu T, et al. The diagnostic and predictive value of AI-combined multilayer spiral CT for MACE after emergency PCI in STEMI patients: A prospective cohort study. Medicine, 2026.PMID 42363530
- [8]Li P, et al. Regional versus general anesthesia for femur and hip fracture surgery: A meta-analysis of postoperative outcomes and complications. J Int Med Res, 2026.PMID 42363795